Evolution, Primate Traits, and Species Divergence: Key Concepts for Biology

What is microevolution?

Change in allele frequency from one generation to the next.

What is macroevolution?

Long-term evolutionary change that results in new species (accumulated microevolution).

What is phyletic gradualism?

Slow, continuous evolutionary change over time.

What is punctuated equilibrium?

Rapid bursts of evolutionary change followed by long periods of stasis.

What is stasis?

No evolutionary change.

What is anagenesis?

One species gradually becomes another; ancestral species goes extinct.

What is cladogenesis?

One species splits into multiple species; ancestral species remains.

What is allopatric speciation?

Speciation caused by geographic isolation.

What is sympatric speciation?

New species arise in the same geographic area.

What is extinction?

No surviving members of a species remain.

What is a species?

A group of naturally interbreeding organisms that produce fertile offspring.

What is a sub-species?

Morphologically distinct group with little/no interbreeding due to geography.

What is phylogeny?

Evolutionary history of species based on shared traits.

What are homologous structures?

Shared traits due to common ancestry.

What is convergent evolution?

Independent evolution of similar traits in unrelated species.

What is a clade?

An ancestor and all its descendants.

What is a node?

A point where species diverge.

What are defining primate traits?

Opposable thumbs, nails not claws, stereoscopic vision, long ontogeny, forward-facing eyes.

What is encephalization?

Increased brain size relative to body size.

What is heterodonty?

Differentiated teeth (incisors, canines, molars).

What are nocturnal animals?

Active at night.

What are diurnal animals?

Active during the day.

What are key traits of strepsirrhines?

Wet rhinarium, post-orbital bar, tapetum lucidum, dental comb, grooming claw.

What is the dentition of strepsirrhines?

2-1-3-3 (usually).

What are examples of lorisiformes?

Lorises, galagos.

What is an example of lemuriformes?

Lemurs of Madagascar.

What are key traits of haplorrhines?

Dry nose, reduced olfaction, post-orbital closure.

What are tarsiers known for?

Huge eyes, nocturnal, vertical clinging and leaping.

What are traits of platyrrhines?

2-1-3-3 dentition, broad/splayed nostrils, some have prehensile tails.

What is special about marmosets/tamarins?

Twin births + cooperative caregiving.

Why are howler monkeys loud?

Enlarged hyoid bone.

What is the dentition of catarrhines?

2-1-2-3.

What are traits of cercopithecoids?

Ischial callosities, bilophodont molars.

What are cercopithecines?

Cheek-pouch monkeys (e.g., baboons, macaques).

What are colobines?

Leaf-eating monkeys with chambered stomachs.

What are key traits of hominoids?

Y-5 molars, no tail, long development, adapted for brachiation.

What are traits of gibbons?

Best brachiators; throat sacs.

What are orangutan traits?

Sexual dimorphism, cheek flanges in males.

What is the gorilla social system?

One-male, multi-female troops.

What are chimp traits?

Patriarchal, aggressive, infanticide, hunting.

What are bonobo traits?

Matriarchal, peaceful, plant-heavy diet.

Why do chimps and bonobos differ?

Food availability—bonobos have abundant ground food; chimps compete with gorillas.

What are advantages of group living?

Defense, access to mates, cooperative care.

What are disadvantages of group living?

Competition, disease, visibility to predators.

What are three types of predator defense?

Detection, deterrence, dilution.

What is alloparenting?

Non-parents caring for infants.

What are solitary primates?

Orangutans, tarsiers.

What is an example of polygyny?

Gorillas.

What is an example of polyandry?

Marmosets.

What is an example of polygynandry?

Chimps, baboons (fission-fusion).

What are pair-bonded primates?

Gibbons.

What is philopatry?

Remaining in the natal group.

What are the effects of dominance?

Higher rank = more mating success + better infant survival.

What is sexual dimorphism?

Morphological differences between males and females.

Which mating system has the highest dimorphism?

Polygyny (one-male, multi-female).

What is estrus?

Female reproductive receptivity window.

What does infanticide accomplish?

Returns mother to estrus sooner.

How do females reduce infanticide risk?

Mate with multiple males to create paternity confusion.

What is grooming?

Social bonding + stress reduction behavior.

What is altruism?

Helping another at a cost to oneself.

What explains altruism evolutionarily?

Kin selection.

What is ontogeny?

Growth and development.

What did the Harlow studies show?

Social + emotional behavior is learned and requires bonding.

What is the most encephalized part of the primate brain?

Neocortex.

What is a rhinarium?

Moist nose pad of strepsirrhines.

What are the continents where primates are found?

Central/South America, Africa, Asia.

What is VCL?

Vertical clinging and leaping.

What is the prehensile tail group?

Platyrrhines.

What are bilophodont molars?

Two ridged molars in Old World Monkeys.

What is fission-fusion?

Temporary foraging subgroups.

What is cooperative breeding?

Helpers assist in raising offspring.

What is sexual selection?

Traits evolve for mating success.