Unit 4 Flashcards
What 2 groups of animals does the Primatomorpha include?
The dermaptera and primates
What are the dermapteras?
Small group of Southeast Asian gliding mammals
What 2 groups are the primates divided into?
Wet nose (strepsirrhines) and dry nose (haplorhines)
Lemurs, galagos, lorisids are a part of the __ group of primates
Wet-nose (strepsirrhines)
Tarsiers, monkeys, and apes are part of the __ group of primates
Dry-nose (haplorhines)
The __ are a group including monkeys and apes
Simians
Baboons, macaques, gibbons, great apes, humans are the ____ primates
Old world catarrhines (narrow-nosed)
Capuchins, howler and squirrel monkeys are the ___ primates
New world platyrrhines (flat-nosed)
What percent of all mammals are rodents?
40%
Glires include ___ and ___
Rodentia and lagomorpha
Phylogenetics attempts to determine evolutionary relationships between ___
Taxa
What is a clade?
The common ancestor and all of its descendants
A ___ is when a phylogeny only shows relationships among species
Cladogram
Terms of a phylogenetic tree
___ indicate a point in a phylogeny where the lineage splits
Nodes
___ are the terminal end of an evolutionary tree
Tips
What is the pattern of branching of a phylogenetic tree called?
Topology
What is a monophyletic group?
A clade – group made up of an organism and all its descendants
What is a polyphyletic group?
A group of species with different common ancestors
What is a paraphyletic group?
A group that contains a common ancestor but not all of the descendants
What is phenetics?
Grouping taxa together based on their overall similarities. Assumes that more closely related taxa should be similar
What are 2 problems with the phenetic method?
Unequal evolutionary rates and homoplasy
What is homoplasy?
Similarity in a trait not due to shared descent
What is cladistic phylogenetics?
Grouping species together because they share ancestral (plesiomorphic) or derived (apomorphic) characters
What is homoplasy caused by?
Parallelism/convergence and reversal
What is maximum parsimony?
Choosing a tree with the fewest number of changes
What is maximum likelihood?
Choosing a tree with highest probability of the model
Assumes explicit model of evolution
What is the comparative method?
Comparing the pattern of variation across species to understand the evolution of a trait
How many species are on earth?
About 8.7 million
What is speciation?
Biological process by which a single lineage of organisms splits into 2 distinct species
What is species concept?
A scientifically relevant and applicable definition of a species
Morphological species concept
A species is based on a body shape and similarities in structure
Problems with morphological species concept
Sexual dimorphism
Phenotypic differences within a species
Taxa that are morphologically similar but distinct in other ways
Ecological species concept
A species is a group adapted to a particular set of resources in its environment
Problems with ecological species concept
Different populations in a species having different niches
Phylogenetic species concept
A species is the smallest set of organisms that share an ancestor and can be distinguished from other sets
Members must share common descent
Problems with phylogenetic species concept
Phylogenies are hypotheses
Difficult to determine degree of difference for each species
Biological species concept
Species are a population that are reproductively isolated from other groups
Gene flow within species
Problems with biological species concept
Asexually reproducing species
Extinct taxa
Natural hybridization occurs
Allopatric populations possibly being able to mate with each other
What are ring species?
2 populations that don’t interbreed are connected by a loop of populations that are interbreeding
Explained by biological species concept well
Most evolutionary biologists believe ____ species concept is the most useful
Biological species concept is most useful
Anagenesis
When 1 species evolves into another over a long period of time
Does not increase biodiversity
Cladogenesis
When 1 species splits into 2 species
Cladogenesis 3 steps
- Genetic isolation of different populations
- Genetic divergence of each population when in isolation (migration is 0)
- Reproductive isolation (no gene flow)
Prezygotic isolating barrier
Prevents initial formation of zygote
Postzygotic isolating barrier
Barrier after the formation of the hybrid zygote
Limits fitness of the hybrid
Examples of intrinsic postzygotic barriers
Hybrid sterility, hybrid inviability
Examples of extrinsic postzygotic barriers
Behavioral sterility, ecological inviability
Dobzhansky-Muller incompatibilities
Negative epistasis
Hybrid of 2 species will have negative epistatic interactions between alleles that arose independently in each species
Haldane’s Rule
When one sex of the offspring of a hybrid cross is absent, then that sex is the heterogametic sex (XY)
Examples of prezygotic barriers (5)
Mechanical isolation
Gametic isolation
Habitat isolation
Behavioral isolation
Temporal isolation
What is reinforcement?
Natural selection strengthening species boundaries after secondary contact
The Ecdysozoans includes all animals that grow by ___
Ecdysis (animals thats molt their exoskeleton)
Arthropods represent more than ___ of all described animal species
80%
Character displacement
Changes that occur when 2 similar species inhabit same environment
Allopatric speciation
Occurs when a species separates to 2 groups that are isolated from each other
Parapatric speciation
Partial physical separation of populations
Sympatric speciation
No physical separation of populations
Sympatric and parapatric speciation require…
Strong selection or polyploidization
What is polyploidization?
Causes by nondisjunction of chromosomes during mitosis or meiosis
Results in instant speciation
Common in plants, rare in animals
What is required for sympatric speciation?
- Niche preference differences
- Niche adaptation
- Assortative mating
Neogene period
23 - 2.6 million years ago
Early primates and early humans
Quaternary period
2.6 million years ago to present
