Hypotheses on the Adaptive Origins of Primates Flashcards
What does the primate pattern represent?
An adaptation to an arboreal habitat or to life in the trees
This theory suggests that primates evolved features suited for living in trees.
What are some key adaptations of primates for an arboreal lifestyle?
- Grasping hands
- Stereoscopic vision
- Rotatable shoulder joints
What is a major objection to the Arboreal Theory?
Other orders have arboreal species that do not share the primate pattern
Examples include opossums, treeshrews, squirrels, and raccoons.
What does the Visual Predation Theory propose?
The primate pattern represents an adaptation to foraging for insects in the terminal branches of trees
What similarities are found in the Visual Predation Theory?
Similarities to other visual predators such as felines and raptors
What are the objections of the Visual Predation Theory?
*Fails to explain the development of larger primates
*Stereoscopic vision present in non-primates
*Visual predators with lateral eye sockets
What is the Angiosperm Radiation / Coevolution theory?
Primates coevolved with flowering plants, leading to adaptive radiation
What does adaptive radiation refer to?
The evolutionary process by which a species diversifies to occupy different ecological niches
How did primates benefit from flowering plants according to the Angiosperm Radiation theory?
- New niches for feeding
- Role as pollinators and seed dispersers
What are the objections to the Angiosperm Radiation theory?
*Angiosperms first appear in the fossil record millions of years before the first primates
*Some mammals had grasping hands before flowering plants
Who are Carpolestes Simpsoni?
An archaic primate that provides support for the primate/angiosperm coevolution theory
What does the Snake Predation Theory suggest?
Grasping hands and feet developed in response to the need to detect snakes
What adaptation aids in detecting snakes according to the Snake Predation Theory?
Orbital convergence and better depth perception breaks camouflage
When did primates first appear in the fossil record?
Roughly 65 million years ago
What factors influenced primate evolution?
- Global climate changes
- Natural disasters
- Continental drift
What are refugia?
Areas that have high amounts of endemism, hypothesized to be former refuges
What is an endemic species?
A species unique to a specific area
What can be inferred about the diet of extinct animals?
Teeth and chewing muscle inserts
What characteristics identify frugivores?
- Large incisors
- Flat molars
What characteristics identify folivores?
- Small incisors
- Large molars with shearing crests
*Well developed muscles
How do ranging patterns differ between frugivores and folivores?
- Frugivores tend to have large ranges
- Folivores tend to have small ranges
What is sexual dimorphism?
Differences in size or appearance between males and females
What mating system is associated with large male canines?
Polygynous mating system
What dispersal pattern is seen in Cercopithecines?
Male biased dispersal
What dispersal pattern is seen in Colobines
Both sexes disperse
What is the dispersal pattern in New World Monkeys?
Female biased or both sexes disperse
