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bio 220 > midterm 1 vocab > Flashcards

midterm 1 vocab Flashcards

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Biology 101 flashcards
1
Q

what are the steps to the scientific method?

A

observation, hypothesis, measurements, results, conclusion (accept)

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2
Q

goal of stats

A

make strongest conclusion possible with limited information

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3
Q

2 main uses of stats

A

estimation (descriptive) and hypothesis testing (inferential)

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4
Q

population

A

total “universe” of all possible observations

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5
Q

sample

A

set of characteristics that make up subset of the population

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6
Q

variables

A

characteristics of individuals (age, color, etc.)

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7
Q

data

A

measurements of variables made on a sample (yellow/purple, male/female, etc.)

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8
Q

types of variables

A

numerical/quantitative or categorical/qualitative

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9
Q

types of numerical observations

A

continuous (range) or discrete (only select data values, counting)

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10
Q

types of qualitative data

A

nominal (no order) or ordinal (ordered)

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11
Q

what determines the type of stats test used?

A

type of variables and number of treatments

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12
Q

4 reasons why the sample can differ from the population

A

imprecision error (tools/tech), biological variability, mistakes (user error), non-representative data (bias)

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13
Q

bias

A

systemic differences between sample estimations and true population characteristics

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14
Q

random

A

every individual has an equal and independent chance of being selected for sample

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15
Q

purpose of random sampling

A

reduce bias and spread experimental error over all observations/treatments

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16
Q

types of bias

A

order, seasonal (only observing during a certain time of year), observer (Menke is a better evology info observer)

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17
Q

descriptive stats

A

describing a population based on sample data

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18
Q

what does descriptive stats measure?

A

central tendency (mean, median, mode) and spread (SD, variance, range)

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19
Q

what makes a good hypothesis?

A

identification of dependent and independent variables and is testable (can be run through tests) and falsifiable (can be proven wrong)

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20
Q

independent variable

A

predictor or explanatory, causes a response

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21
Q

dependent variable

A

response, the effect one is interested in

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22
Q

what does hypothesis testing do?

A

compare means while considering spread and sample size

calculates the probability of observing the results assuming the null hypothesis is true

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23
Q

what does the p-value represent?

A

probability

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24
Q

when can we reject the null hypothesis?

A

when the p value is less than 5%

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25
Q

t-tests are for testing __ categories

A

2

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26
Q

ANOVA tests are for testing __ categories

A

3 or more

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27
Q

what are mechanisms for evolution (changes in allele frequency)?

A

natural selection, sexual selection, mutations, genetic drift, bottlenecks, and founder effects

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28
Q

what are founder effects?

A

when a small colony of the original population becomes its own separate population, leading to a reduced amount of genetic variation bc the group is small (violates “large” HW)

not adaptation!

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29
Q

what are bottlenecks?

A

a population’s size is reduced for one or more generations, leading to reduced genetic variation (violates “leaving” HW)

not adaptation!

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30
Q

what is genetic drift?

A

the random occurrence of shifts in allele frequency over time

not adaptation!

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31
Q

what is gene flow?

A

movement of individuals to/from a population (violates “leaving/coming” HW)

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32
Q

what is natural selection

A

mechanism of evolution that promotes adaptation for biological fitness (violates “advantageous genotypes” HW)

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33
Q

what are mutations?

A

where genetic variation comes from! random changes in genetic material

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34
Q

what is a species?

A

individuals who can interbreed

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35
Q

population

A

individuals in the same location that can interact and interbreed

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36
Q

what is the result of evolution?

A

genotype and environment -> development of phenotype

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37
Q

what is an allele?

A

multiple forms of a given gene that result in the production of different forms of a protein specified by that gene

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38
Q

A POPULATION IN HW EQ. IS NOT _____!!

A

EVOLVING

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39
Q

why do we use HW if it never really occurs?

A

it can serve as a null hypothesis in evolution studies and is an approximate mathematical model

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40
Q

natural selection acts on ___

A

populations!

changes in individuals over time as a population

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41
Q

effects of evolution are seen in ___

A

populations and species

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42
Q

evolution does not necessarily lead to ___

A

adaptation

evolution isn’t purposeful

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43
Q

microevolution

A

changes in allele frequency within a population

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44
Q

macroevolution

A

large evolutionary changes beyond the formation of a new species (origin of mammals)

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45
Q

when does natural selection occur?

A

when there is variability that is heritable and that influences fitness

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46
Q

scientific theory

A

body of statements that is strongly supported by all evidence we know of and explains some aspect of nature

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47
Q

ecology

A

the study of interactions between organisms and their physical and living environment

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48
Q

proximate factors

A

direct cause of a biological process/phenomenon

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49
Q

ultimate factors

A

deeper cause of a phenomenon that explains when it occurs

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50
Q

organismal level

A

level in hierarchy of biology pertaining to the individual

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51
Q

population ecology

A

study of the interactions between a group of individuals of a given species and their environment

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52
Q

ecological community

A

a group of coexisting species

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53
Q

ecosystem

A

all the biotic and abiotic components of a community

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54
Q

biosphere/ecosphere

A

all ecosystems on Earth

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55
Q

biotic

A

biological factors

predation or competition

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56
Q

abiotic

A

physical factors

temperature or pH

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57
Q

environmental science

A

the study of humans’ impact on the environment

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58
Q

adaptation

A

a trait or characteristic that increases a individual’s fitness in a specific environment

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59
Q

evolutionary fitness

A

an individual’s ability to survive and reproduce as determined by its characteristics

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60
Q

selection pressure

A

biotic and abiotic environmental factors that determine fitness

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61
Q

homeostasis

A

regulatory mechanisms that help an organism stay within a given set of biological parameters/limits

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62
Q

who can have fitness?

A

individuals

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63
Q

predictions

A

a result or observation that we can expect if the hypothesis is true

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64
Q

falsifiable

A

trait of a good hypothesis that allows for data/observation to prove it is incorrect

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65
Q

adaptations are ___ created

A

evolutionarily

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66
Q

what did Darwin establish?

A

natural selection as a mechanism for evolution via adaptation to promote evolutionary fitness

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67
Q

natural selection occurs to…

A

populations

NOT INDIVIDUALS!

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68
Q

p = ___ allele

A

dominant

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69
Q

q = ___ allele

A

recessive

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70
Q

evolution

A

changes in allele frequency

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71
Q

HW equilibrium (math)

A

p^2 + 2pq + q^2 = 1.0

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72
Q

when is HW equilibrium applicable?

A

when no mutations or gene flow occur, the population is infinitely large and randomly mating, and there are no advantageous genotypes

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73
Q

genetic drift

A

random change in allele frequency

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74
Q

gene flow

A

net movement of alleles because of individuals’ movement in/out

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75
Q

s

A

selection coefficient, proportion of a specific genotype not represented in the next generation

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76
Q

directional stability

A

favoring one side of the phenotypic bell curve

one extreme trait

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77
Q

stabilizing selection

A

intermediate trait is favored in phenotypic bell curve

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78
Q

disruptive selection

A

favoring extreme traits over intermediate ones

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79
Q

evolutionary trade-offs

A

when a given characteristic has fitness advantages, but also costs

think of colors and reflectance of guppies

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80
Q

why is genetic drift not darwinian?

A

occurs by chance, not because of natural selection

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81
Q

chronic genetic drift can lead to …

A

allele loss and/or fixedness

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82
Q

gene flow can do what to natural selection?

A

promote or slow the process

incoming/outgoing individuals alter allele frequencies

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83
Q

phenotypic plasticity

A

ability of organisms to present different phenotypes in different environments

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84
Q

heritability

A

cause of phenotypic variation because of genetic differences between individuals

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85
Q

rate of evolution is determined by …

A

changes in character over time

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86
Q

strong selective pressures can lead to ___ and eventually ___

A

more distinct local changes in species and an ecotype

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87
Q

ecotype

A

genetically distinct population that has adapted to a local environment

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88
Q

limits of natural selection

A

physical and chemical limitations (like size)

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89
Q

evolutionary landscape

A

3D model of fitness and particular genotypes that identify best genotypes for evolutionary fitness by tallest peaks

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90
Q

example of organisms with sex roles reversed

A

jacanas or seahorse

male incubates egg (more energetically invested), females compete and are more aggressive

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91
Q

sexual selection occurs when:

A

there’s a heritable variation of a trait that influences mating success or fertilization success

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92
Q

which sex often experiences stronger sexual selection?

A

the competing sex

logic: non-competing sex can get with whoever they want, but competing one is limited. there’s more selective pressure on the limited one to pass on genes

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93
Q

elaborate traits usually occur in the ___ sex

A

competing

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94
Q

sexual selection can occur:

A

before or during/after sex

intrasexually or intersexually

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95
Q

example of intrasexual selection before mating

A

mooses

male-male or female-female competition for access

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96
Q

example of intersexual selection before sex

A

peacocks

display by competing sex for mating choice by non-competing sex

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97
Q

example of intrasexual selection d/a sex

A

frogs

compete to have their sperm fertilize egg

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98
Q

example of intersexual selection d/a sex

A

“cryptic mate choice”

female chicken can choose which sperm fertilizes their egg after sex

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99
Q

intrasexual selection

A

individuals within a sex compete DIRECTLY for access to mates and their gametes

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100
Q

examples of evolution of traits for intrasexual selection

A

weaponry, fast sperm, sexual size dimorphism

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101
Q

sexual size dimorphism

A

competing sex is larger

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102
Q

intersexual selection

A

indirect competition for access to mates and their gametes

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103
Q

what traits can help intersexually selecting organisms win access to mates?

A

mating displays and signals, courtship behavior, or genitalia

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104
Q

sexual selection is the result of:

A

direct or indirect competition for mates

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105
Q

benefits of sexual reproduction must ___ ___ ___

A

overcome non-trivial costs

pros of only passing on 1/2 of genetic material must be better than the cons of potentially risking survival

think: color of guppies finding balance between mating visibility and predation avoidance

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106
Q

sexual selection often results in traits that ___ natural selection

A

oppose

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107
Q

where does natural variation come from?

A

mutations!

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108
Q

process of including mutation in population

A

created, generates alleles, natural selection hopefully favors it, adaptive trait selected

109
Q

selection ___ ___ ___

A

edits existing variation

110
Q

genes are:

A

composed of DNA and specify how to build proteins

111
Q

what are mutations caused by?

A

DNA copying errors, chemicals, or ionizing radiation

112
Q

what is important about ionizing radiation?

A

can’t reach gametes

113
Q

frequencies of mutation can change due to:

A

meiosis/recombination, natural selection, genetic drift, or gene flow

114
Q

mechanisms that DECREASE variation

A

stabilizing selection, inbreeding, and genetic drift

115
Q

“silent” or “synonymous” mutations

A

don’t change the amino acid

116
Q

“nonsynonymous” mutations

A

change amino acids and potentially the function of the following protein, can then be acted upon by NS

117
Q

what are the structural mutations that can occur?

A

deletion, duplication, inversion, fission, or fusion

118
Q

mutation rates are very low! so…

A

mutations likely won’t change allele frequencies in one generation

119
Q

recombination during meiosis can …

A

exchange maternal and paternal chromosomes to produce new combinations more rapidly

120
Q

what is the molecular clock?

A

Kimura’s theory that most mutations are neutral

we accumulate mutations constantly and we can use that to date how long ago different populations diverged

a lot of DNA isn’t used much (has since been disproven) and mutations of thrid codon don’t always have an impact

121
Q

phenotypic plasticity

A

a change in an individual’s PHENOTYPE in response to their environment

122
Q

natural selection example:

A

soapberry bugs

introduction of new host plants with different fruit sized, bugs shifted hosts

NS resulted in beak adaptation to reach seed

123
Q

what are the types of selection?

A

directional, disruptive, and stabilizing

124
Q

example of directional stabilization

A

darwin’s finches in the drought

favored large beaks to open harder seeds

125
Q

example of stabilizing selection

A

gall-making flies

larvae produce galls on goldenrod plants, but large and small galls were targeted by predation, so intermediate size was favored

126
Q

example of disruptive selection

A

african seedcrackers (birds)

small beaks can eat soft seeds, large can eat hard, medium aren’t optimal for their

127
Q

what does stablizing selection do?

A

maintain mean and reduce variance

128
Q

what does disruptive selection do?

A

maintain mean and increase trait variance

129
Q

what does directional selection do?

A

change the mean and potentially reduce trait variation

130
Q

sexual selection

A

selection due to within-population competition for access to mates and their gametes

131
Q

sexual selection is responsible for:

A

more diverse and extravagant traits in nature, rapid evolution, and increased speciation

132
Q

anthropomorphism

A

attributing human traits or intentions to non-human entities

innate tendency that we should avoid with this content

133
Q

sexual selection occurs as a result of ___

A

variation in mating success

not everyone gets to mate or the same amount of mates

134
Q

what causes variation in mating success?

A

competition

135
Q

gametes are the ___

A

main difference between males and females

136
Q

egg

A

large and sessile gametes

137
Q

sperm

A

small and mobile gamete

138
Q

sexual possiblities

A

none (no gametes), two separate sexes (lions), hermaphroditism, sequential hermaphroditism

139
Q

hermaphroditism

A

male and female gametes are produced in the same individuals

common in plants

140
Q

sequential hermaphroditism

A

individual start life as one sex and later transition into the other

141
Q

sex roles

A

dependent on differences in parental investment between sexes

142
Q

higher parental investment ->

A

limiting sex, has mating preferences

143
Q

lower parental investment ->

A

limited sex, has mating competition

144
Q

anisogamy

A

differences in gamete size

145
Q

our ancestral state is ___

A

isogamy

146
Q

isogamy

A

single mating type, everyone can mate with everyone else

all gametes are same size

universal compatibility

147
Q

gamete trade-offs

A

large but slow/non-moving gametes with lots of resources vs. small but faster gamete with little resources

148
Q

anisogamy is ___ distributed

A

disruptively

149
Q

Bateman’s principle

A

in most species, females invest more in reproduction than males, making them the limiting sex

150
Q

male lifetime fitness is limited by …

A

how many mates they can obtain

151
Q

female lifetime fitness is limited by…

A

how much resources they have available to allocate reproduction

152
Q

result of Bateman’s principle?

A

females can be the more choosy sex and males have to compete for them

roles can be reversed

153
Q

can phenotypic plasticity evolve?

A

yes, it can be an adaptation

ability to get fit more efficiently is heritable, but looking fit is not a heritable trait

154
Q

reactive norm

A

range of phenotypic expressions of genotype across range of environments

155
Q

example of phenotypic plasticity

A

male horned beetles

use horns and body size to fight for females

morphology determined by amount of food in larval period

why spend resources on large body is you have small horns and you’ll lose anyways?

156
Q

common garden experiment

A

individuals with different phenotypes are grown under same conditions

157
Q

genetically controlled in GCE if…

A

individuals maintain their wild traits

158
Q

phenotypic plasticity in CGE if…

A

individuals shift to similar traits

159
Q

what is the purpose of the common garden experiment

A

distinguishing genetic variation from phenotypic variation

160
Q

what are mechanisms that maintain genetic variation?

A

meiosis/recombination, natural selection, gene flow, disruptive selection, negative frequency-dependent selection

161
Q

mechanisms that decrease genetic variation

A

stabilizing selection, inbreeding, genetic drift, positive frequency-dependent selection

162
Q

frequency dependent selection

A

fitness of individual is dependent on its relative frequency amongst the population

163
Q

positive frequency-dependent selection

A

majority phenotype wins

reduces genetic variation in population

think mullerian mimicry butterflies

164
Q

mullerian mimicry

A

two poisonous species mimic each other

whatever looks like this won’t get eaten

165
Q

negative frequency-dependent selection

A

minority phenotype wins, promotes genotypic and phenotypic variation in population

166
Q

example of negative frequency-dependent selection

A

purple/yellow morph flowers

naive pollinators will switch between them as they search for different reward (nectar/pollen)

167
Q

sampling effects

A

changes in allele frequency over time that are random with respect to their function or selection

168
Q

founder effect

A

loss of genetic diversity bc of migration event in which smaller group “founds” their own population

169
Q

example of founder effect

A

less genetic diversity as humans spread out from Africa

170
Q

bottleneck effects

A

loss of genetic variation from dramatic reduction in population size and then recovery from it, new population descends from small number

171
Q

example of bottleneck effect

A

northern elephant seals

hunting reduced population to 20-40 individuals, today have extremely low genetic variation

172
Q

genetic drift

A

changes in allele frequencies in population due to chance events

173
Q

random sampling effects can lead to…

A

differences in numbers, sex ratio, or survival of offspring

174
Q

genetic drift leads to…

A

evolution at random

175
Q

example of genetic drift

A

beetles being crushed by shoe image

176
Q

4 conclusions about genetic drift

A

its is unbiased, affects smaller populations ore, decreases genetic diversity over time, and generates divergence among populations

imagine plots of multi-colored lines

177
Q

endangered species example

A

florida panther

caused by: poaching, vehicle collisions, habitat loss, and fragmentation

178
Q

extinction vortex

A

cycle of factors worsening extinction status

179
Q

in extinction, drift can increase…

A

inbreeding load

can increase the frequency of deleterious alleles

180
Q

example of morphological sign of inbreeding

A

kinked tails in florida panthers

88% had them in florida, only 9% in other cougar species

181
Q

what does increase in genetic variation allow for?

A

better survival of the species

can better withstand disease or deleterious alleles

182
Q

what mechanisms of evolution did cheetahs experience?

A

genetic drift, bottleneck, and inbreeding

183
Q

biological species concept

A

species are groups of interbreeding natural populations that are reproductively isolated from other such groups

184
Q

what is the biological species concept largely based on?

A

reproductive isolation

185
Q

limitations of biological species concept

A

1) problematic for species that can’t feasibly be tested for reproductive isolation (spatial/temporal differences)

2) issues with getting species to mate in artificial conditions

3) hybridization is more common than we think

186
Q

steps to speciation

A

1) genetic isolation
2) divergence of traits accumulate
3) reproductive isolation

187
Q

vicariance

A

physical barrier causing dispersal

188
Q

geological events

A

river formation, mountain ranges rising, continental drift

189
Q

example of vicariance by climate change

A

pleistocene period

cycle of glacial and interglacial periods that can lead to refugia and separate populations

190
Q

refugium

A

places that isolated populations of once widespread species survive major environmental changes

191
Q

species that experienced speciation by climate change vicariance

A

toucanets

found glacial period refugia in separating forest canopies, but as they disconnected the species behaviorally wouldn’t fly to other areas and they speciated

192
Q

continental drift

A

movement of landmasses on earth’s surface

193
Q

consequences of continental drift on ecological systems

A

creates and breaks down barriers for dispersal

weather impacted as positioning of continents and major oceans influences weather patterns

194
Q

examples of vicariance by continental drift

A

pangaea (one large) -> gondwana and laurasia (two regions) -> n/s america, afria, asia, antarctica (5 regions)

195
Q

population impacted by continental drift for speciation

A

ratites - type of flightless bird

hypothesized they lived together in gondwana but as it fragmented, they were split apart and then speciated

196
Q

genetic isolation can occur by…

A

physical barriers (vicariance), dispersal, or genetic barriers

197
Q

dispersal example

A

islands or “sky islands”

198
Q

what are sky islands?

A

mountain tops for alpine species with extreme arid climate in valleys between

species don’t behaviorally move from mountain top to mountain top because of these climate differences

199
Q

examples of genetic barriers for dispersal

A

polyploidy, major chromosomal changes, other genetic changes

200
Q

genetic barrier to dispersal meaning

A

egg and sperm can’t fertilize each other

201
Q

polyploidy problem

A

incompatible amounts of chromosomes

202
Q

example of genetic isolation by genetic barrier

A

tree frogs

Hylaversicolor = tetraploidy
H. chrysosceli = diploid

versicolor likely originated from chrysoscella genome duplication

morphologically identical but different mating calls

203
Q

diverge

A

accumulation of differences from each other (when populations have separated)

204
Q

what can cause mutations to become fixed/lost in different populations?

A

selection and/or genetic drift

205
Q

many species ___ reach full reproductive isolation

A

DON’T

hybridization can happen more often than we may think

206
Q

what are the classifications of isolating barriers?

A

premating, postmating prezygotic, postzygotic

207
Q

what are premating barriers

A

prevention of transfer of gametes

208
Q

what are postmating prezygotic barriers?

A

mating occurs, but zygote doesn’t form

209
Q

examples of prezygotic barriers

A

ecological (temporal, habitat, etc. prevent mates from meeting)

sexual isolation or pollinator isolation (can meet, but don’t ex: different mating calls or female not attracted to male)

210
Q

what is temporal isolation?

A

periods of reproduction or emergence aren’t compatible

think cicadas in 13/17 yr cycles

211
Q

what is habitat isolation?

A

species occupy different habitats in same geographic region

think ladybugs feeding and mating on different species of plants

212
Q

what are postzygotic barriers?

A

mating occurs, and zygote forms but hybrids have lowered fitness

213
Q

examples of postzygotic barriers

A

heliconius butterflies- hybrids have lower fitness because they don’t have appearance that camouflages them as poisonous species like parental species do (example of positive frequency-dependent selection, parent surviving bc of majority pheotype)

214
Q

what are the two models of speciation?

A

allopatric and sympatric

215
Q

what is allopatric speciation

A

speciation in non-overlapping regions

more common

1) physical barrier
2) no gene flow
3) genetic differentiation

216
Q

what is sympatric speciation?

A

speciation in overlapping regions

1) temporal/seasonal/ecological barrier
2) individuals can still come in contact and there can be significant gene flow
3) significant genetic differentiation

217
Q

reminder about speciation

A

species ranges are subject to change, can be sympatric at one time and then allopatric at another

218
Q

examples of sympatric speciation

A

1) soapberry bugs
- adaptation of different beak lengths because of introduction to nonnative plant (smaller fruit)

2) palms of Lord Howe island
- early flowering couldn’t transfer pollen to later flowering ones

219
Q

convergent evolution

A

organisms evolving to have similar traits because adapting to similar environments

not necessarily recent common ancestor

220
Q

example of convergent evolution

A

sugar glider (oceania) and flying squirrel (north/central america)

221
Q

what is phylogeny?

A

evolutionary history of a group

222
Q

what does a phylogeny tree do?

A

summarize evolutionary history

can depict timing and pattern of branching events

most closely related species should have the most traits in common

223
Q

choose parsimonious tree

A

this will minimize the amount of evolutionary change, keep it simple!

224
Q

keep in mind, phylogenies are ___

A

hypotheses

based on data we have

225
Q

homo sapiens are the ___ ___ of an otherwise extinct group of species

A

lone survivor

226
Q

how long ago did human and chimp lineages diverge?

A

about 6-7 million years ago

227
Q

what preceded H. sapiens?

A

several other species of hominin

228
Q

what does hominin mean?

A

any species more closely related to human than chimpanzee

229
Q

how are H. sapiens and chimps different?

A

1) fully upright posture
2) relatively hairless
3) smaller incisors
4) fully opposable thumbs
5) larger brain size for language
6) recognition of complex cause and effect
7) development of complex culture

230
Q

anatomical differences between chimps and humans

A

1) flat face
2) long legs, short arms
3) very different pelvis shape
4) anterior foramen magnum (head is more central on spine, not sitting in forward posture)
5) s-shaped spine
6) curved feet

230
Q

what is not so special about humans?

A

technology/tool use

innovation

communication

cultural inheritance (evolution of a culture over time)

231
Q

what are all anatomical differences adaptation for?

A

bipedalism

232
Q

what is a trade off for our bipedalism traits?

A

terrible childbirth

a lot of complications and death

233
Q

additional differences between humans and chimps

A

a) extremely fine motor control (hands, lips, tongue, oral cavity)
b) opposable thumbs and shorter fingers
c) descended larynx (trade off: choking)

234
Q

cost of humans having larger brains

A

higher metabolic rate relative to fat-free body mass than chimps, gorillas, and orangutans

235
Q

what’s an important consideration when forming a phylogenetic tree other than appearance?

A

geography

236
Q

benefits of humans having larger brains

A

social brain hypothesis

237
Q

social brain hypothesis

A

living in large social groups could have resulted in natural selection that favored larger brains

bigger groups are more successful because of cooperation and accumulated and transmitted knowledge

we need big brains for language to maintain those large groups’ organization

238
Q

what does radiation mean?

A

the rapid evolution of multiple species from a single ancestor

239
Q

why do we not have a great understanding of human evolution?

A

we have a lot of incomplete skeletons because hominin bodies are terrible at fossilization, which is what we base a lot of ancestry info on

there’s also a lot of closely related lineages, leading to a lot of uncertainty

240
Q

what are some limitations of fossil records?

A

we don’t know when hominins lost body hair or started wearing clothing

241
Q

lice

A

are highly specialized blood sucking parasites that live on a single host species

a lot of ape relatives have one species, humans have three

242
Q

co-speciation hypothesis

A

two sets of two species diverge at the same time

in terms of humans and chimps, their lice diverged at the same time as them (6-7 mya)

243
Q

where is it hypothesized that humans picked up pubic lice?

A

early gorillas

sleeping in nests that were recently used by them or preying on them (lice are known to jump from prey to predator)

244
Q

we can use phylogenies to…

A

test hypotheses about speciation

such as when hominins lost body hair or started wearing clothing

245
Q

key events in human evolution

A

1) shrewlike ancestors climbed scrubs and trees 80 mya

2) arboreal ancestors provided humans with binocular visions and skillful hands

3) as african climate dried, ancestors descended from trees 5-10 mya

246
Q

all lineages of hominins originate in africa except…

A

neanderthals, denisovans, and H. floresiensis

247
Q

what lineages migrated out of africa?

A

h. erectus, h. heidelbergensis, and h. sapiens (in that order)

248
Q

other lineages that originated outside of africa

A

h. floresiensis, h. neanderthalensis, and denisovans

249
Q

where did h. floresiensis originate?

A

indonesia

250
Q

where did h. neanderthalensis originate?

A

europe

251
Q

where did denisovans originate?

A

siberia

252
Q
A
253
Q
A
254
Q

other hominins spread out of africa at least ___, before humans did so

A

twice

led to new populations establishing and speciation events due to isolation and divergence

all but h. sapiens went extinct

255
Q

basic info of homo erectus

A

first lineage to leave africa

long lineage, existed for about 1.5 my

extinction likely due to climate change

never coexisted with h. sapiens

256
Q

range of h. erectus

A

all over africa, parts of europe, south and east asia, indonesia

migration led to new populations establishing

speciation event in indonesia originated h. floresiensis

257
Q

h. floresiensis basic info

A

skull the size of modern day toddler’s

in indonesia

258
Q

why were h. floresiensis skulls so small?

A

likely bc of island dwarfism

259
Q

island dwarfism

A

typically large organisms evolve to have smaller bodies when on smaller geographic areas, like islands

260
Q

island gigantism

A

opposite of island dwarfism

typically small animals evolve to have larger bodies when on smaller geographic areas, like islands

261
Q

h. heidelbergensis basic info

A

second lineage to leave africa

migration led to new populations establishing

speciation events due to isolationg and divergence: neanderthalensis in europe, denisovans in asia, h. sapiens in africa

262
Q

homo sapien basic info

A

originated in africa from heidelbergensis population that didn’t migrate

continued to evolve in africa until 60 kya, 2000 individuals migrated out of africa

all humans outside of africa descended from those 2000 individuals - founder’s effect

much higher genetic diversity within native african populations what between populations on different continents

263
Q

what is the leaky replacement hypothesis

A

genes of other species of humans are still around today in non-african populations due to hybridization

not a complete replacement by h. sapiens, some genetic mixing involved

“leaky” = genes still around due to hybridization

264
Q

out of africa hypothesis

A

h. sapiens spread out from africa and replaced existing species of hominins, such as neanderthals or denisovans with no interbreeding

265
Q

multiregional continuity hypothesis

A

modern humans didn’t originate from a single population in african but as multiple interconnected populations around the world

also evolved from h. erectus

disproven bc ethiopian fossils are the oldest ones we’ve ever found

266
Q

why were h. sapiens likely the lone survivor?

A

neanderthals and denisovans were better adapted to colder climates

during interglacial periods, h. sapiens were able to expand upward and compete with other hominids for their niche

h. sapiens had potential advantages: bigger brains, larger populations, pelvis adaptations for running, and division of labor in group living

267
Q

evidence of founders effect in humans

A

more deleterious mutations as we move away from africa

less genetic variation and less room to evade them

bio 220 (11 decks)

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