Ch.29: Evolutionary Genetics Flashcards
What is a species?
a group of individuals whose members can interbreed to produce viable, fertile offspring; members of one species cannot successfully interbreed with members of other species
What are the 2 ways to achieve reproductive isolation?
-Prezygotic isolating mechanisms that prevent the formation of a zygote (ex. habitat, temporal, mechanical, or gametic isolation)
-Postzygotic isolating mechanisms prevent the development
of a viable individual after fertilization has taken place (ex. hybrid inviability, sterility, or breakdown)
What is the biological species concept?
a species is a group of individuals whose members have the
potential to interbreed with one another in nature to produce viable, fertile offspring but cannot successfully interbreed with members of other species
What is the evolutionary species concept?
A species should be defined based on the separate evolution of lineages
What is the ecological species concept?
Each species occupies an ecological niche, which is a unique set of habitat resources the species requires
What is the general lineage concept?
-Each species is a population of an independently evolving lineage and has evolved from a specific series of ancestors, so each forms a group of organisms with a particular set of
characteristics.
-Multiple criteria are used to determine if a given population is part of an independent evolutionary lineage; morphology, reproductive isolation,
DNA sequence and ecology
-Most researchers agree that the general lineage concept is the best way to define species
What is Anagenesis?
A single species is transformed into a different species over
the course of many generations
What is Cladogenesis?
A single species is divided into two or more species; This is the most common form of speciation
What is allopatric?
Two large populations are separated by geographic barriers
or a small population separates from the main population and
becomes geographically separated
What is Parapatric?
Two populations are partially separated geographically
What is Sympatric?
A small group evolves into a reproductively separate species
Does not involve geographic separation
What is phylogeny? What is a phylogenetic tree?
-the sequence of events involved in the evolutionary development of a species or group of species
-A phylogenetic tree is a diagram that describes the phylogeny
of a species
What are the 2 different approaches to construct a phylogenetic tree?
-Phenetic approach: Trees are constructed by comparing overall similarities without trying to understand evolutionary history
-Cladistic approach: Trees are constructed by choosing the best amongst various paths of evolution
What is an ingroup?
a species or group of species that is monophyletic or derived
from a common ancestor – an ingroup is related
What is an outgroup?
a species or group of species that are ancestral or more
distantly related – an outgroup is not related
What is the Principle of parsimony?
the preferred hypothesis is the one that is the simplest
What 2 genes are said to be homologous if they are derived from the same ancestral gene?
-Orthologous genes/orthologs: homologous genes found in different species
-Paralogous genes/paralogs: homologous genes found within a single species
What do fossil records show the mammalian timeline of earth as?
Monkeys -> Gorillas -> Humans
What is the most genetic variation observed in natural populations due to?
the accumulation of neutral mutations
What has the Kimura “neutral theory of evolution” has been called?
“survival of the luckiest theory” and also non-Darwinian evolution in order to contrast it with Darwin’s “survival of the fittest theory” ; believed most modern variation in
gene sequences is explained by neutral variation
How does the advent of molecular techniques help with the analysis of
chromosomes from different species?
-can help researchers identify regions that contain the same groups of linked genes, or synteny groups
-Within a particular synteny group, the same types of genes are found in the same order
