bio 316 exam 3 wku

phylogeny

Evolutionary history of a group of species

Phylogenetic tree

Diagram showing evolutionary relationships among taxa

Systematics

Field focused on building and evaluating phylogenies

Taxa

Groups of organisms (species, genera, etc.)

Phylogenies are hypotheses

They can be tested, revised, and falsified

Evolutionary lineage

Ancestor-descendant sequence over time

Genetic linkage

Connection between organisms and ancestors via DNA

Homology

Similarity due to shared ancestry.

Analogous traits

Similarity due to function, not ancestry.

Convergent evolution

Independent evolution of similar traits.

Plesiomorphy

Ancestral trait.

Apomorphy

Derived trait.

Synapomorphy

Shared derived trait defining a clade.

Autapomorphy

Derived trait unique to one taxon.

Homoplasy

Similarity not due to common ancestry.

Monophyletic group

Ancestor + all descendants.

Paraphyletic group

Ancestor + some descendants.

Polyphyletic group

No recent common ancestor.

Cladistics

Method using shared derived traits.

Willi Hennig

Founder of cladistics.

Parsimony principle

Simplest explanation with fewest changes preferred.

Ockham's Razor

Simplest explanation is best.

Character matrix

Table of taxa vs traits.

Character state

Trait condition (present/absent).

Coding

Using 0 (absent) and 1 (present).

Ingroup

Group being studied.

Outgroup

Reference group (more ancestral).

Nodes

Branch points (common ancestors).

Clade

Group sharing a common ancestor.

Steps of cladistic analysis

Choose taxa, characters, outgroup, build matrix, code, find synapomorphies, group taxa, draw tree, label nodes.

Morphological data

Physical traits.

Molecular data

DNA or gene sequences.

Gene tree

Tree based on genes.

Species tree

Tree based on species relationships.

Total evidence approach

Using multiple data types.

Synapomorphies

Unite taxa; shared derived traits define groups.

Autapomorphies

Do not unite groups.

Ancestral vs derived traits

Context-dependent classification.

Whale evolution question

Relationship to artiodactyls vs perissodactyls.

Astragalus bone

Key synapomorphy of artiodactyls.

Parsimony in whale evolution

Fewer steps supports whale-hippo relationship.

Adaptation

Trait increasing fitness.

Fitness

Contribution to next generation.

Adaptationist program

Observe trait, test function, measure fitness benefit.

Hypothetico-deductive method

Testable hypotheses prevent 'just-so stories'.

Mutualism

Both species benefit.

Parasitism

One benefits, other harmed.

Oxpecker study

Showed relationship may be parasitic, not mutualistic.

Comparative method

Compare species to study adaptation.

Trade-off

Improvement in one trait reduces another.

Constraint

Limitation on evolution.

Example constraint

Frogs tied to water reproduction.

Example trade-off

Fish schooling vs competition.

Begonia example

Trade-off between flower size and number.

Sexual reproduction

Requires two parents, increases variation.

Asexual reproduction

Single parent, low variation.

Sexual dimorphism

Differences between males and females.

Sexual selection

Differences in mating success.

Natural selection

Differences in survival and reproduction.

Intrasexual selection

Competition within same sex.

Intersexual selection

Mate choice between sexes.

Parental investment

Energy/time invested in offspring.

Eggs vs sperm

Eggs costly, sperm cheap.

Bateman's principle

Males vary more in reproductive success.

Limiting factor

Males limited by mates, females by offspring production.

Male behavior

Competitive.

Female behavior

Choosy.

Sperm competition

Sperm compete to fertilize eggs.

Strategies in sperm competition

More sperm, removal of rivals, mate guarding.

Infanticide

Killing offspring to increase reproductive success.

Female choice

Selection based on traits.

Sexy sons hypothesis

Attractive males produce attractive offspring.

Resource hypothesis

Females choose males providing resources.

Nuptial gifts

Males provide food/resources for mating.

Kin selection

Natural selection favoring relatives.

Inclusive fitness

Direct + indirect fitness.

Direct fitness

Own reproduction.

Indirect fitness

Helping relatives reproduce.

Coefficient of relatedness (r)

Probability of shared genes.

Parent-offspring r

1/2.

Full siblings r

1/2.

Half siblings r

1/4.

Cousins r

1/8.

Hamilton's Rule

Br - C > 0; B benefit to recipient, C cost to actor, r relatedness.

Altruism favored when

High B, low C, high r.

Altruism

Behavior benefiting others at cost to actor.

Cooperation

Both benefit.

Selfish

Actor benefits, recipient harmed.

Spiteful

Both harmed.

Alarm calls

Warn others, may be altruistic.

Ground squirrels

Whistles selfish, trills altruistic.

Prairie dogs

Call more when kin present.

Helping behavior

Individuals help relatives raise offspring.

Bee-eaters

Helpers increase offspring survival.

Parent-offspring conflict

Different fitness interests.

Sibling rivalry

Competition among siblings.

Eusociality

Extreme social system.

Characteristics of eusociality

Overlapping generations, cooperative care, division of labor.

Haplodiploidy

Males haploid, females diploid.