Evolution of Life Histories:

Allocation of time and energy throughout organism's life usually requires 4 processes

growth

survival

reproduction

defense

But in reality organisms will evolve to maximze reproduction given the tradeoffs

reproduce once and die

ie fish

iteroparous organisms

reproduce repeatedly

humans

high over most of lifespan, many live long

many chances for future reproduction

offspring survivorship is high

increases with age, but few live long

few chances for future reproduction

offspring suvivorship is low

eggs are expensive

sperm are cheap

accounts for bizarre structures

differential reproduction as a result of variation in the ability to obtain mates

individuals with werid traits are better at obtaining mates

strategies of reproduction

male vs. female

females- invest more E in offspring, produce fewer offspring, increase fitness with quality offspring and tend to be choosy

males- invest little in offspring, can fertilize eggs, increase fitness with many offspring, tend to be promiscuous

selection leads to differences in body characteristics

behavior, coloration and ornamentation

Before courtship- compete for resources or females

During coutship and mating- males try to displace on another

After Courtship but before fertilization- sperm competition

After Fertilization, but before birth- induced abortion

After Birth- infanticide

elabortate traits decrease survivorship

males with handicap must have great genes

trait is flexibly expressed, not all males have it

evolution is self reinforcing

trait will runaway

exaggeration stops when expression is too costly

this is a positive feedback loop

Alternative Mating Strategies

Satellite strategy

hang out on edge of territory intercept incoming females

Alternative Mating Strategy

Sneaker Strategy

Frequency dependent selection

itness depends on frequency

self limiting process -- can result in balanced polymorphism

gene pools can follow sepertate paths which are reproductively isolated

Reproductive Isolation

Prezygotic Barriers

Reproductive Isolation

Postzygotic Barriers

zygote development

offspring survival

offspring reproduction

Speciation

What Causes barriers to arise?

geography

local adaptation

genetic drift

disuptive selection

sexual selection

Types of Speciation

Allopatic Speciation

Types of Speciation

Peripatirc Speciation

Types of Speciation

parapatric speciation

evolution of reproductive barriers in continuous populations, that hav gene flow by selection imposed by different habitats

Types of Speciation

sympatric speciation

prevalent in platns (50%) of plant lineages

a doubling of chromosome number that leads to instant reproductive isolation

tetraploid (4N)

Tpyes of Speciation

Polyploid Speciation

autopolyploid- unreduced gametes fuse from same spcies

allopolyploidy-  unreduced gametes fuse from different species

responsible for generating new forms of organism

genetic changes within and among populations

evolution of species and higher taxa

The History of Life

Goal of Determining Life

Start with choosing groups of interest

then choose characters to classify groups

speies- geneus- family- order- class- phylum - kingdom