ANP 220 fundamentals of evolutionary theory II

natural selection

by which the individuals best adapted to the environment contribute more offspring to succeeding generations than others do

• favors traits that enhance ability to survive and reproduce

• acts on ALL individuals EQUALLY

adaptation

a trait that better suits an organism to its environment

• improves chances of survival and reproduction

• usual result of natural selection

fitness

reproductive success (surviving offspring)

• combines survival, mate find reproduction (offspring production and survival

surviving to old age is not everything

example of adaptation guppies

spots on guppes

• size genetically controlled to help blend in

experiment

• with predators

  • blend in with background

• how many individuals with small and large spots

why the number of mates matters a lot for fitness

sexual selection

• category of natural selection

• favors traits that increase success in access to mates

• acts on individuals in ONE SEX only

forms of sexual selection

• intrasexual selection (male) competition (winner)

• female mate choice (best)

mechanisms of evolutionary change

• non-adaptive - mutation - gene flow - genetic drift

• adaptive - natural selection - sexual selection

• inter means between

• intra means within

major questions

In what way do characters change

• stasis (uncaged) slow, fast direction

In what way do species evolve

• single lineage evolving, lineage, splitting

biological evaluation

definition

• descent with inherited modication

  • change through time

  • genetic inheritance

small scale

• population level

  • microevolution

large scale

• population level

  • macroevolution

→ explains biodiversity

small scale

• population level

  • microevolution

change within species from one generation to the next over few generations

large scale

• population level

  • macroevolution

change over many generations, species divergence new species

mechanisms

• short term similar

• both micro and marco

macroevolution

• concerned with species and higher taxonomic levels

What is a species - species concept - biological species concept (BSC)

a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such populations

species concepts - more than two dozen concepts

reproducing fertile offspring

• producing fertile offspring

mate recognition species concept

• recognizing one another as protentional mates

ecological species concept

• exploiting or adapted to a single niche

phylogenic species concept (PSC)

smallest uniquely identifiable cluster wit parental pattern of ancestry and descent example: orangutans on Sumatra and Borneo and elephants

mode of species origin I

cladogenesis - branching evolution involving the splitting of a species

mode of species origin II

anagenesis - single species undergoes gradual cane and transforms over time

causes of speciation

• geographic isolation - reduction of gene flow

• necessary for speciation - reproductive isolation - difference in mating - lack of fit sexual organs - offspring non-viable / sterile

allopatric speciation

interbreeding populations (gene flow)

barrier prevents interbreeding (no gene flow)

isolated populations may develop differently (natural selection, mutation, genetic drift, founder effect

two new species (do not interbreed even if they meet)

pace of evolution

phyletic gradualism - change is consistent and slow

punctuated equilibrium - periods of little and rapid change

learning objectives or what i should know