Kin selection/speciation (W5-L1)

Individuals sacrifice their own evolutionary fitness for others Cannot evolve by individual selection, cheaters would be favored

Personal reproduction

Reproduction by relatives, made possible by an individuals actions

The sum of an individuals reproduction through relatives made possible by indirect action and its own reproduction In order to have a positive effect on the individual, the benefit of alturism must exceed the cost to the alturist

Mechanism of increasing inclusive fitness through apparent alturism

br>c b=benefit to the recipient r=coefficient of relatedness of an alturist recipient c=cost to the alturist

• benefit to the recipient is great • cost to altruist is low • participants are closely related

1) drawn all paths 2) multiply probabilities 3) Add probabilities across paths

• Altruistic behavior will be disproportionately directed towards close relatives (higher r) • if individuals disproportionately help kin, they must be able to recognize kin from non-kin

Extreme altruism: • overlapping generation • cooperatives brood care • reproductive and non-reproductive castes Only found in groups that build complex nests, care for larvae for extended periods, large ecological component

When new species form from mutation, gene flow, genetic drift, natural selection, sexual selection

• species are groups that evolve independently from other such groups (independent evolutionary lineages) • Individuals of the same species contribute to the same gene pool • species may consist of several interbreeding populations • taxonomic distinction “species” is the smallest independent evolutionary unit • To identify a species is to hypothesize the boundaries of gene flow

Groups of actually or potentially inbreeding organisms that are reproductively isolated from other such groups

Absence of gene flow between groups of individuals due to intrinsic features of organisms

• focuses on gene flow - grouping principle clear (i.e. breeding vs nonbreeding)

• hybridization between good species • ring species • asexual organisms don’t interbreed • populations are often geographically separate • Fossils

geographical features like mountains, rivers, ocean, forests that prevent gene flow (geographic isolation)

Genetically based properties of organisms that limit gene flow (reproductive isolation)

Features that prevent individuals from creating a zygote ex. Ecological differences, temporal differences, sexual (behavioral) differences, gametic imcompatibility

features that prevent zygote from developing into a healthy and/or fertile adult ex. Zygote mortality, hybrid inviability, hybrid sterility, other hybrid problems

When 2 groups of one species are isolated geographically and diverge into separate species The simplest and most common mechanism of speciation

no specific extrinsic barrier to gene flow • population is continuous, but it does not mate randomly • mating with geographic neighbors more often • divergence occurs from reduced gene flow within the population and variation selection processes

Does not require geographic isolation to reduce gene flow between parts of a population • exploiting a new niche may automatically reduce gene flow between individuals exploiting another niche • ex. herbivores insects moving to another plant species