Species Concept and Mechanics of Speciation Flashcards
1
Q
making of species
A
speciation
2
Q
species diverge gradually over time in small steps
A
gradual speciation model
3
Q
a new species changes quickly from the parent species and then remains largely unchanged for long periods of time afterward
A
punctuated equilibrium model
4
Q
all species on earth thought to share a single __ __
A
common ancestor
5
Q
when did life arise
A
3.8 billion years ago
6
Q
speciation is the generation of __ __ __
A
species level diversity
7
Q
what processes lead to genetic differences sufficint to create a new species
A
- Natural selection
- Mutation
8
Q
external
A
natural selection
9
Q
internal
A
mutation
10
Q
may have occured billions of times in the last 3.8 billion years
A
speciation
11
Q
all cultures recognize different forms (species) and name them
A
naming
12
Q
different species in groups
A
classifying
13
Q
the challenge of scientists is to name and classify species in a testable way
A
system
14
Q
number of living species may be as great as ____
A
100 million
15
Q
is the evolutionary biology subfield that deals with taxonomy, understanding speciation, describing species, inferring phylogenies, and similar endeavors
A
systematics
16
Q
what is a species
A
smallest independently evolving unit
17
Q
When does independent evolution occur
A
- mutation
- selection
- gene flow
- genetic drift
operate indpendently in different populations
18
Q
change in the DNA sequence of an organism
A
mutation
19
Q
process in nature by which organisms better adapted to their environment tend to survive and reproduce more than those less adapted to their environment
A
Natural selection
20
Q
- transfer of genetic material from one population to another
- can take place between two populations of the same species through migration, and is mediated by reproduction and vertical gene transfer from parent to offspring
A
Gene flow
21
Q
- change in frequency of an existing gene variant in the population due to random chance
- may cause gene variants to disappear completely and thereby reduce genetic variation
- cause initially rare alleles to become much more frequent, and even fixed
A
Genetic Drift
22
Q
Four basic species concept
A
- Biological Species Concept
- Morphological Species Concept
- Ecological Species Concept
- Evolutionary Species Concept
23
Q
- defines a species taxon as a group of organisms that can successfully interbreed and produce fertile offspring
- a species’ integrity is maintained by interbreeding within a species as well as by reproductive barriers between organisms in different species
A
Biological Species Concept
24
Q
Problems with Biological Species Concept
A
- is irrelevant to allopatric speciation
- inapplicable to:
(1) fossil species
(2) organisms reproducing asexually or with extensive self-fertilization
(3) sexual organisms with open mating systems (species that freely hybridize)
25
defines species as groups of individuals that are morphologically similar to one another and are morphologically distinct from other such groups
morphological species concept
26
advantages of morphological species concept
1. traditional and simple
2. applicable for living and extinct
3. applicable for asexual and sexual
4. on-spot (ready to use as reference)
27
disadvantages of morphological species concept
1. cryptic species (comprise two or more taxa under single name)
2. does not address genetic differences
28
- concept of species in which a species is a set of organisms adapted to a particular set of resources, called a niche, in the environment
ecological species concept
29
describes the role an organism plays in a community
niche
30
species integrity in ecological species concept is not so much maintained by __ __, but by selection to adapt to each species to its niche
reproductive isolation
31
disadvantages of ecological species theory
- Too many decisions on how much difference between individuals is too much variation
- Nearly the entire are made up of non-identical individuals
32
- is a single lineage of ancestor-descendant populations of organisms
- maintains its identity from other such lineages (in space and time)
- has its own evolutionary tendencies and historical fate
evolutionary species concept
33
advantages of evolutionary species concept
- conceptually clear
- applies to asexual species, through time, and allopatric species
34
population or species that is physically isolated from other similar groups by an extrinsic barrier to dispersal
allopatric species
35
disdvantages of evolutionary species concept
- difficult to know the future
- asexual species have too many indepent lineages
36
- practical approach of dealing with the more philosophically grounded evolutionary species concept
phylogenetic species concept
37
two-step process to define species in phylogenetic species concept
1. grouping taxa
2. ranking groups by the criterion of finding the smalles diagnosable monophyletic groups
38
disadvantage of phylogenetic species concept
- almost any population can be diagnosed
- gene trees may not follow species trees
39
logic of phylogenetic species concept is that traits can only distinguish populations on a phylogeny if the populations have been
- isolated in terms of gene flow
- have diverged genetically and/or morphologically
40
a population of organisms that is considered distinct for purposes of conservation
evolutionarily significant unit (ESU)
41
The "classic" process of speciation
1. isolation
2. divergence
3. sometimes secondary contact
42
isolation
- physical barriers
- allopatry
- dispersal
- vicariance
43
division of the population due to the appearance of a new geographical barrier
vicariance
44
divergence
- drift
- natural or sexual selection
45
sometimes secondary contact
- hybridization
- reinforcement
- fusion
46
grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor
clade
47
what can be an isolating factor
anything that causes a reduction in gene flow between two potential species
48
physical (geographic) isolation resulting in speciation
allopatric speciation
49
alloparty can be due to...
- dispersal (movement)
- vicariance (encroaching physical feature)
50
= separation of species by physical barriers like water forms, oceans, mountains, etc
Geographical isolation
51
heritable condition of possessing more than two complete sets of chromosomes
polyploidy
52
speciation without any physical isolation
sympatric isolation
53
how does polyploidy happen
non-disjunction during meiosis
54
mechanism that keeps species from mating with other
Reproductive isolation
55
two types of reproductive isolation
1. prezygotic isolation
2. postzygotic isolation
56
separation of different species to keep them from creating offspring by preventing the gametes from forming a zygote
prezygotic isolation
57
What are the different prezygotic barriers
1. temporal isolation
2. habitat isolation
3. behavioral isolation
4. gametic barrier
5. mechanical barrier
58
differences in breeding schedules
temporal isolation
59
populations of a species move to a new habitat and overimte, forces of natural selection, mutation, and genetic drift will likely result in divergence
habitat isolation
60
presence/absence of a specific behavior prevents reproduction from taking place
behavioral isolation
61
differences in gamete cells prevent fertilization from taking place
gametic barrier
62
reproductive structures simply do not fit
mechanial barrier
63
isolation occurs after members of two different species have mated and produced a zygote
Postzygotic isolation
64
What are the different postzygotic barriers
1. hybrid inviability
2. hybrid sterility
65
hybrid individuals cannot form normally in the womb and simply do not survive past embryonic stages
hybrid inviability
66
reproduction leads to birth and growth of a hybrid that is sterile and unable to reproduce offspring of their own
hybrid sterility
67
biotic factors
- competition
- predation
- prey
68
abiotic factors
climate
69
phenomenon in which two or more species with effective defenses share a similar appearance or signaling
Müllerian mimicry
70
example of animal that were influenced by their habitats in terms of their mating preferences
cichlid fish
71
emphasizes the importance of the environment in shaping perception and thus preferences
Sensory drive
72
Speciation via sensory drive in cichlid fish:
- higher frequency of red LWS allele and more red males found in deeper waters
73
the evolutionary process by which many species originate from one species in an area and radiate to different species
Adaptive radiation
74
Any of a group of different types of individuals of the same species in a population
morphotype
75
what drives diversification
- larger range size
- more opportunity to get into new habitats
