Evolution Lecture 12

Front 1

Culex pipiens molestus (Sister group to culex pipiens)

Back 1

Breeds underground in confined spaces; bites mammals rather than birds; active all year rather than being dormant in winter; does not recognize its sister group as potential mates

Front 2

BSC: Biological Species Concept

Back 2

Defines species in terms of interbreeding; doesn't work with archaea or bacteria because they do not have sex

Front 3

MSC: Phenetic (Morpho) Species Concept

Back 3

A species is a set of organisms that look different from other organisms; Linked to taxonomy, cataloging organism traits; authority; Only current method for paleontology (lacks DNA)

Front 4

ESC: Ecological Species Concept

Back 4

Looks at niche boundaries and competition (you will be competing the most with someone just like you) to categorize species; NOT commonly used

Front 5

PSC: Phylogenetic Species Concept

Back 5

All you have to do is develop data sets, then use phyloanalysis to see where they fall on a phylogenetic tree; as the potential to yield way too many species; boundaries can be arbitrary

Front 6

Allopatric speciation

Back 6

A geographic speciation that occurs when biological populations of the same species become vicariant, or isolated from each other to an extent that prevents or interferes with genetic interchange.

Front 7

Parapatric speciation

Back 7

Extremely rare; occurs when populations are separated not by a geographical barrier but by an extreme change in habitat. While populations in these areas may interbreed, they often develop distinct characteristics and lifestyles.

Front 8

Sympatric speciation

Back 8

The process through which new species evolve from a single ancestral species while inhabiting the same geographic region.

Front 9

Theodisius Dobzhansky

Back 9

Researched reproductive isolation, and what happens to create barriers

Front 10

Ernist Mayr

Back 10

Came up with the different types of speciation, was an advocate of allopatric speciation, believed parapatric speciation was rare (it's not, in plants)

Front 11

Cline

Back 11

Gradient shift from one habitat to another

Front 12

Vicariance

Back 12

The division of a population due to a physical phenomenon ex) ground squirrels are different species on either side of the Grand Canyon

Front 13

Shrimp

Back 13

Evidence of allopatry is found as the tips of the tree have all divided into a Pacific Shrimp and Caribbean Shrimp

Front 14

Bounded Hybrid Superiority

Back 14

When a hybrid forms on the edge of two habitats; a bridge between two species of plants

Front 15

Ring species

Back 15

California salamanders that formed a ring around the Central Valley, and where they meet back up they are not compatible

Front 16

Polyploidy

Back 16

Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes.

Front 17

Autopolyploidy

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An individual or strain whose chromosome complement consists of more than two complete copies of the genome of a single ancestral species.

Front 18

Allopolyploidy

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An organism whose cells have multiple sets of chromosomes derived from a different species.

Front 19

Secondary Reinforcement

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When secondary contact between two diverged populations actually pushes the populations further apart; Any hybrids that form are not as fit at either parent

Front 20

Character displacement

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Character displacement is the phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur but are minimized or lost where the species' distributions do not overlap.

Front 21

Dobzhansky's Reproductive Isolating Mechanisms

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Two variations: Prezygotic and Postzygotic

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Prezygotic Isolating Mechanisms

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Potential mates live in the same place but do not encounter one either due to...

-habitat isolation

-temporal isolation

-behavioral isolation

-gametic incompatibility

Front 23

Postzygotic Isolating Mechanisms

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-Zygotes die early in embryogenesis

-Hybrids are inviable

-Hybrids survive but are sterile

-Second generation hybrids are inviable or sterile

Front 24

Isolation through pollinators

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Hawkmoths, Darwin's orchid, etc.

Front 25

Negative epistasis

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When epistasis enacts a severe fitness cost on hybrids (postzygotic barrier to reproduction)

Front 26

Haldane's Rule

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An observation about the early stage of speciation (by the British evolutionary biologist J.B.S. Haldane) that states that if in a species hybrid only one sex is inviable or sterile, that sex is more likely to be the heterogametic sex.

Front 27

Dobzhansky-Muller model

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How does genic incompatibility between species evolve without simultaneously causing defects in pure species? In the ancestral population, the genotype is AA BB. When the population is split into two, A evolves into a in one population and B evolves into b in the other. a and b are mutually incompatible.a in one population and B evolves into b in the other. a and b are mutually incompatible. As the a-b interaction is not present in the pure species, the evolution of incompatibility is possible. Detailed genetic analysis on hybrid male sterility, however, has shown that hybrid incompatibility often involves conspecific genic interactions as well.