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BIOL 214 > BIOL 214 Final (Unit 1) > Flashcards

BIOL 214 Final (Unit 1) Flashcards

1
Q

Descent with modification

A
  1. Individuals compete for limited resources, and
    more individuals are born than can survive and
    reproduce to their full potential.
  2. There is variation within species.
  3. Some of this variation relates to fitness.
  4. Some of this variation is heritable.

Natural selection: Heritable traits that
improve fitness will become more prevalent in
successive generations.

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2
Q

Phylogenetic Trees

A
  • Represent hypotheses about the evolutionary relationships among a group of organisms.
  • A phylogenetic tree may be built using morphological (body shape), biochemical, behavioral, or molecular features of species or other groups.
  • In building a tree, we organize species into nested groups based on shared derived traits (traits different from those of the group’s ancestor).
  • The sequences of genes or proteins can be compared among species and used to build phylogenetic trees. Closely related species typically have few sequence differences, while less related species tend to have more.
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3
Q

Artificial Selection

A
  • Change initiated by humans
  • Operates by favoring individuals with certain phenotypic traits, allowing them to
    reproduce and pass their genes on to the next generation
  • This directional selection should result in evolutionary change
    (includes agricultural selection, which allows for more desirable traits in plants and food)
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4
Q

Fossil Evidence of Evolution

A

Fossils are the preserved remains of once-living organisms
Rock fossils are created when three events occur
- Organism buried in sediment.
- Calcium in bone or other hard tissue mineralizes.
- Surrounding sediment hardens to form rock.
Process of fossilization is rare event

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5
Q

Fossil Formation

A
  • normally the soft remains of organisms are consumed by scavengers or decompose
  • during fossilization, dissolved minerals replace some parts leaving a fossil made of stone
  • fossils can form as molds, casts, or impressions
  • absence of oxygen prevents decomposition and preserves soft-bodied organisms (in some environments)
  • could be embedded in amber or preserved in ice, coal, or tar pits
  • good fossils help to observe anatomy, cell structure, and food in digestive track
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6
Q

advantage of fossils

A

Only fossils can tell us which
organisms with which phenotypes
existed at a given location at a
specific point of time prior to a few
thousand years ago.

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7
Q

disadvantages of fossils

A

Single point in time.
Single fossil does not tell you when
that species appeared, or when
that species went extinct
fossil data is incomplete
spatial/temporal bias
preservation bias

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8
Q

Indirect data from fossils

A

Behavior: Fossilized footprints of some dinosaurs suggest that
adults surrounded their young when the group moved.
* Physiology: Scrolls of bone in nasal passages of early
mammals suggest a well-developed sense of smell.
* Ecology: Fossilized teeth and dung provide data about the
diets of extinct animals.
* Climate: Fossilized pollen and changing arrays of fossils reflect
large-scale shifts in physical environments.

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9
Q

estimating the age of fossils

A

In Darwin’s day, rocks were dated by position relative to one
another
* Today geologists determine the absolute age of rocks using
isotopic dating
* Potassium (K) isotopes vary in number of neutrons,40 K
* half-life is 1.25 bil years
* For more recent events,14 C * half-life is 5700 yea

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10
Q

radiometric dating

A

In radiometric dating, scientists measure the relative amounts
of parent radioisotope and its breakdown products.
* By comparing this ratio with the isotope’s half-life, they can
estimate the absolute age of the rock.

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11
Q

homologous structures

A

Structures with different appearances and functions that all derived from the same
body part in a common ancestor.

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12
Q

vestigial structures

A

Vestigial structures have no apparent function, but resemble structures ancestors
possessed

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13
Q

biogeography

A

Study of the geographic distribution of species

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14
Q

convergent evolution

A

Similar forms having evolved in different, isolated areas because
of similar selective pressures in similar environments

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15
Q

Darwin’s conclusions

A
  • Many islands have never been connected to the mainland.
  • Species arrive on islands by dispersing across the water.
  • Dispersal from nearby areas is more likely than distant sources.
  • Species that can fly, float or swim are more likely to inhabit islands.
  • Colonizers often evolve into many species.
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16
Q

Morphological species concept and its problems

A

All individuals of a species share measurable anatomical traits that
distinguish them from individuals of other species.
- Relying exclusively on morphology can present problems when
there is much variability within a single species, or when two
species are nearly identical in appearance.

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17
Q

biological species concept and its problems

A

groups of actually or potentially interbreeding
natural populations which are reproductively isolated from other such groups
* Species are composed of populations whose members mate with each other and
produce fertile offspring
* Reproductive isolation – do not mate with each other or do not produce fertile
offspring
Reproductive isolation may not be the only force maintaining species integrity.
* Interspecific hybridization
* Difficult to apply the concept to populations that are
geographically separated in nature
* Many species that do not hybridize in the wild will do so in
captivity
* Many organisms are asexual
* Possible that different processes maintain species identity in
different organisms

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18
Q

gene exchange

A

Barriers to successful reproduction are called reproductive isolating mechanisms
* Prezygotic isolating mechanisms: Mechanisms that prevent formation of a zygote.
* Postzygotic isolating mechanisms: Mechanisms that prevent proper functioning of zygotes after they form.

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19
Q

prezygotic isolating mechanisms

A
  • Ecological isolation
  • Behavioral isolation
  • Temporal isolation
  • Mechanical isolation
  • Prevention of gamete fusion
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20
Q

postzygotic isolating mechanisms

A
  • hybrid inviability or infertility
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21
Q

ecological isolation

A

Species occur in the same area, but they occupy different
habitats and rarely encounter each other.

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22
Q

behavioral isolation

A

Species differ in their mating rituals.

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23
Q

temporal isolation

A

Species reproduce in different seasons or at different times
of the day.

24
Q

mechanical isolation

A

Structural differences between species prevent mating.

25
Q

prevention of gamete fusion

A

Gametes of one species function poorly with the gametes of
another species or within the reproductive tract of another
species.

26
Q

hybrid inviability or infertility

A

Hybrid embryos do not develop properly, hybrid adults do not survive in nature, or hybrid adults are sterile or have reduced fertility.

27
Q

Why can adaptation lead to speciation?

A

*As populations of a species adapt to different circumstances, they likely accumulate
many differences that may lead to reproductive isolation
* Changes in dewlap color in lizards related to environment
* If you can’t be seen, you don’t mate.
* Could lead to reproductive isolation from ancestral population.

28
Q

ecological species concept

A
  • Each species adapted to its environment
  • Distinctions among species are maintained by natural selection.
  • Stabilizing selection maintains the species’ adaptations.
  • Hybrids are quickly eliminated from gene pool.
  • In some cases, strong selection overwhelms gene flow.
29
Q

phylogenetic species concept and its problems

A
  • Morphological and genetic sequence data is used to reconstruct an
    organism’s evolutionary tree.
  • A species is defined as a cluster of populations that share a recent
    evolutionary history as shown on the evolutionary tree.
  • Because evolutionary histories have been described for relatively few
    groups, the phylogenetic species concept cannot be applied to all
    forms of life.
30
Q

allopatric speciation

A
  • Geographically separated, or allopatric, populations appear much more likely to have evolved substantial differences leading to speciation
  • Takes place when a physical barrier subdivides a large population, or when a small population becomes separated from a species’ main geographical distribution

occurs in two stages:
* Two populations become geographically separated, preventing gene
flow between them.
* Accumulated genetic differences isolate them reproductively.

31
Q

sympatric speciation

A

One species splits into two at a single locality, without the two new species ever having
been geographically separated
* One type occurs commonly as the result of polyploidy
* Individuals that have more than two sets of chromosomes

considered to be very rare

32
Q

polyploidy

A

autoploidy
* All the chromosomes arise from a single species.
* Error in cell division produces tetraploids.
* Cannot produce fertile offspring with normal
diploids.

allopolyploidy
* Two species hybridize.
* Resulting offspring have one copy of the
chromosomes of each species.
* Infertile: cannot reproduce with either species
chromosomes do not pair correctly in meiosis.
* Can become fertile if chromosomes
spontaneously doubled (polyploidy); breed with
other tetraploids.
40

33
Q

adaptive radiation

A

Closely related species that have recently evolved from a common ancestor by adapting to different parts of the environment

occurs:
- in environment with few other species and many resources
- after catastrophic event leading to extinction of other species

34
Q

key innovation

A

New trait evolves within a species allowing it to use resources that were previously inaccessible

35
Q

modifications of existing structures

A
  • Sometimes a trait that is adaptive in one context is also advantageous under different circumstances.
  • The original version of the trait (exaptation) may be exaggerated or modified to enhance its new function.
36
Q

character displacement

A
  • Two reproductively isolated but ecologically similar species come into contact
  • Natural selection in each species favors those individuals that use resources not used by
    the other species
  • Greater fitness
  • Trait differences in resource use will increase in frequency over time
  • Species will diverge
37
Q

gradualism

A
  • accumulation of small changes
38
Q

punctuated equilibrium

A
  • Long periods of stasis followed by rapid change.
  • Stabilizing and oscillating selection is responsible for stasis.
  • Gradualism and punctuated equilibrium are two ends of a continuum
39
Q

mass extinctions

A
  • 5 mass extinctions have occurred; as many as 96% of all species have perished in a
    given extinction
  • Not all groups of organisms affected equally; previously dominant groups may perish
  • 6th extinction is underway; number of species decreasing at an alarming rate due to
    human activity

ordovician, devonian, permian, triassic, cretaceous

K-T extinction - extinction of non-avian dinosaurs of meteor

40
Q

scientific naming

A

genus name and then species name, and then authority (who named it)

41
Q

hierarchical classification

A
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
42
Q

cladistics

A

ancestral characteristic (plesiomorphy)
* Similarity that is inherited from the most recent common ancestor of an entire
group.
derived characteristic (apomorphy)
* Similarity that arose more recently and is shared only by a subset of the
species.
shared derived characteristics (synapomorphy)

43
Q

cladistic method

A

Characters can be any aspect of the phenotype
* Morphology
* Physiology
* Behavior
* DNA
Characters should exist in recognizable character states

44
Q

homologous characters

A

Any trait inherited from a common ancestor by two or more
species can be described as homologous.
* Homologous characters may differ greatly among species, especially if their function has changed over time.
* Organisms that are not closely related sometimes resemble
one another, especially when they are exposed to similar
patterns of natural selection.
* Phenotypic similarities that evolved independently in different
lineages are called homoplasies (or homoplastic characters).
* Homoplastic characters that serve a similar function in different
species are products of convergent evolution.

45
Q

molecular sequencing and its advantages

A

Because DNA is inherited, shared changes in molecular sequences (insertions, deletions, or substitutions) provide
clues to evolutionary relationships.
Publication of complete genome sequences allows researchers to undertake broad comparative studies.

  • Abundant data – every base in a nucleic acid is a separate,
    independent character for analysis;
  • Can be compared between distantly related organisms that share no
    organismal characteristics;
  • Can be used to study closely related species with only minor
    morphological differences;
  • Nucleic acids are not directly affected by developmental or
    environmental factors that cause nongenetic variations.
46
Q

cladistic analysis

A
  • determine if characters are ancestral or derived
  • use outgroup comparison
  • When the group under study exhibits multiple character states, and one of
    those states is exhibited by the outgroup, then that state is ancestral and other
    states are derived
  • Most reliable if character state is exhibited by several different outgroups
  • Presence of tail in vertebrates is ancestral
  • Absence of tail in some species is derived
47
Q

Clade

A

Cladogram
* Depicts a hypothesis of evolutionary relationships.
Clade
* Species that share a common ancestor as indicated by the possession of
shared derived characters.
* A clade is an evolutionary units and refers to a common ancestor and all
descendants.
* Synapomorphy – derived character shared by clade members.

48
Q

construction of a cladogram

A

plesiomorphies - ancestral states
symplesiomorphies - shared ancestral states

49
Q

homoplasy

A

shared character state that had not been inherited from a common ancestor
- convergent evolution
- evolutionary reversal

50
Q

monophyletic group

A

Includes the most recent common ancestor of the group and all of its descendants (clade).

51
Q

paraphyletic group

A

Includes the most recent common ancestor of the group, but not all its descendants.

52
Q

polyphyletic group

A

Does not include the most recent common ancestor of all members of the
group.

53
Q

nomenclature rules

A
  • the principle of priority requires using first published name/epithet in combination with the legitimate genus name
  • if the epithet + genus combination does not exist yet, publish under new combination
54
Q

molecular clock

A
  • Mitochondrial DNA (mtDNA) evolves relatively quickly – it is
    useful for dating evolutionary divergences within the last few
    million years.
  • Chloroplast DNA (cpDNA) and genes that encode ribosomal
    RNA evolve much more slowly, providing information about
    divergences that date back hundreds of millions of years.
  • Molecular clocks must be calibrated using the fossil record, or
    biogeographically with independent data.
55
Q

homoplastic convergence

A

similar traits evolve independently in different clades

56
Q

comparative biology

A

Most complex characters do not evolve in one step
Evolve through a sequence of evolutionary changes

57
Q
A

BIOL 214 (1 decks)

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