Evolution Final

Anisogamy

production of different sized gametes

few large, many small

Sexual selection exists bc females produce relatively ___ ____ gametes and males produce ______ ______ gamete

males

Which sex invests less in their gametes

equal

Average reproductive success between sexes must be ____

charles darwin

first defined sex roles

sex roles

behaviors associated w/ males or females in terms of reproduction

males

Defined by darwin as competitive sex

Bateman gradients

show strength of sexual selection acting on the sexes

females

Bateman gradients described which as the limiting sex?

relative

Is fitness based on absolute or relative numbers?

operational sex ratio

ratio of sexually active males to number of fertilizable females

no, skewed towards males

is the operational sex ratio typically 1:1?

high variation

When operational sex ratio is skewed towards males, tends to be ________ in reproductive success

sex role reversal

Occurs if males are the limiting sex

traits that improve success in confrontation and avoidance of contests with superior rivals

what do same sex contests select for?

Residency status

the individual who owns the resource is more likely to win a conflict for it

virgin

males are more willing to take risks for ______ females

an arms race

Directional selection for competition favored traits can cause _________ that results in even more extreme traits

Territoriality, mate -guarding, reducing female receptivity, copulatory plugs

How do males reduce likelihood other males will mate?

pre-copulatory guarding

male guards female before mating occurs

sperm-competition

occurs when sperm of 2 or more males have the opportunity to fertilize a female’s eggs

sperm precedence

pattern of sperm used by females in fertilization (could be last or first)

larger, more exaggerated

Females often mate with males with ________ characters.

direct

what type of benefits are nutrition, territory, parental care, fertilization assurance?

indirect benefits

female benefits from success of her offspring sired bt genetically superior males

runaway sexual selection

evolution of traits that are only sexually attractive -> not directly or indirectly beneficial in terms of survivorship

good gene models

-Females should evolve to choose males with high genetic quality
-Any male trait w/ genetic quality could be used by females as guide

condition dependent

Female preference for male indicator traits should be most likely to evolve if the trait is a _________ indicator of fitness

good

males in "___" condition court in higher rates

higher

Females mated to males in good condition have ______ fitness

sexy sons hypothesis

Sons of attractive males show higher fitness

nuptial gift-giving

males bring offering of food to females in exchange for mating opportunity

gene flow

individuals move from one population to another bringing new frequencies of alleles

high

_____ gene flow makes frequencies in different populations more similar.

differentiate

no gene flow causes species to _______

mutation, selection, genetic drift

What causes allelic frequencies to diverge when gene flow ends?

species

-distinct types of organisms
-evolutionary independent groups

species concepts

Used to identify species

biological species concept

-oldest and most frequently used species concept, identifies groups that naturally or potentially interbreed
-reproductive isolation from other groups

isolating mechanisms

Dobzhansky's proposition that adaptions prevent an individual from bearing unfit hybrids.

Hybrid breakdown

F1 generation is viable and fertile but F2 generation is not

prezygotic

Behavioral isolation is a form of _______ isolation

prezygotic isolation

prevents zygotes from certain populations/species from forming

postzygotic isolation

isolation that keeps populations separate after a zygote has formed, zygotes not sucessful

habitat isolation

organism populations do not live on the same habitat which prevents gene flow

temporal isolation

species are separated by the timing of their reproduction which prevents gene flow

behavioral isolation

gene flow prevention seen in populations that use very different courtship behaviors

gametic isolation

opportunity for fertilization, but it does not occur because the gametes are incompatible

reduced hybrid viability

zygotes can be produced but fail to complete development

reduced hybrid fertility

hybrids of species are viable but are sterile creating genetic dead end

hybrid breakdown

F1 generation is both viable and fertile however F2 generation will not be either viable or fertile

habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

types of prezygotic isolation

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

types of postzygotic isolation

morphospecies concept

-often used when reproductive isolation cannot be determined
-evolutionarily independent lineages based on distinguishing features

traits used to distinguish species are subjective

main disadvantage of morphospecies concept

lumpers

tend to argue for natural variation and group more species together

phylogenic species concept

-based on reconstructing evolutionary history of populations
-a species is smallest monophyletic group distinguished by a shared derived character

phylogenetic species concept

With which species concept is there concern that it recognizes many more species than the others?

Allopatric speciation

Evolution of reproductive barriers in populations prevented from migrating to each other by geographic barrier

vicariance or dumbbell model

type of allopatric speciation. one large population is divided into 2 equally sized daughter population and migration is prevented, caused genetic differences to accumulate in the populations

Parapatric speciation

populations share a border but do not overlap and diverge

Sympatric speciation

Evolution of reproductive barriers within a single population

Peripatric speciation or peripheral model

small population splits from parent population, differences accumulate and become genetically incompatible

allopatric

what is thought to be the most common form of speciation

adaptive divergence, reproductive isolation

allopatric populations and species undergo both _________ and evolution of _______

female choice

models of sexual selection of male traits by _______ show divergent traits can evolve in different populations of an ancestral species

reinforcement of reproductive isolation

once differences start to accumulate in a population due to one type of isolation, other isolation mechanisms tend to act in addition

weaker

in parapatric speciation, gene flow is ____ than divergent selection

disruptive

What type of selection can lead to sympatric speciation

host races

genetically differentiated, sympatric populations of parasites that feed on different hosts

polyploidy

can create instant speciation and is common in plants

reduced hybrid fertility

What type of isolation is isolation by polyploidy

time for speciation

The time required for reproductive isolation to evolve

biological species interval

the average time between origin of a new species and when that species branches again

varies greatly

The rate of speciation _____

biodiversity and branching phylogeny

What are the consequences of speciation?