Chapter 24 Flashcards
the process by which one species splits into two or more species, is at the focal point of evolutionary theory.
Speciation
consists of changes in allele frequency in a population over time
Microevolution
refers to broad patterns of evolutionary change above the species le
Macroevolution
states that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with members of other such groups
Biological Species Concept
is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with members of other such groups
Species
is the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring
Reproductive Isolation
are the offspring that result from mating between different species
Hybrids
block fertilization from occurring by
Impeding different species from attempting to mate
Preventing the successful completion of mating
Hindering fertilization if mating is successful
Prezygotic Barriers
What isolation is where Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers
Habitat Isolation
What isolation is when Species that breed at different times of the day, different seasons, or different years cannot mix their gametes
Temporal Isolation
An isolation that happens when Courtship rituals and other behaviors unique to a species are effective barriers to mating
Behavioral Isolation
An isolation that happens when Morphological differences can prevent successful completion of mating
Mechanical Isolations
an isolation when Sperm of one species may not be able to fertilize eggs of another species
Gametic Isolation
Prevent the hybrid zygote from developing into a viable fertile adult by:
Reduced hybrid viability
Reduced hybrid fertility
Hybrid Breakdown
Postzygotic Barrier
The biological species concept can be applied to fossils or asexual organisms (including all prokaryotes)
True or false?
False (It cannot be applied)
can occur between morphologically and ecologically distinct species
Gene Flow
defines a species by structural features
*It applies to sexual and asexual species but relies on subjective criteria
Morphological Species Concept
defines a species in terms of its ecological niche
*It applies to sexual and asexual species and emphasizes the role of disruptive selection
Ecological Species Concept
Speciation can occur in two ways what are these?
Allopatric and Sympatric
gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations
Allopatric Speciation
What Isolation may arise as a by-product of genetic divergence?
Reproductive Isolation
Can develop between experimentally isolated laboratory populations subjected to different environmental conditions
Reproductive Barriers
This speciation has also been observed in nature
Allopatric Speciation
A Speciation occurs in populations that live in the same geographic area
Sympatric Speciation
Sympatric speciation can occur if gene flow is reduced by factors including what?
Polyploidy, Sexual selection and Habitat differentiation
is the presence of extra sets of chromosomes due to accidents during cell division
is much more common in plants than in animals
Polyploidy
is an individual with more than two chromosome sets derived from a single species
The offspring resulting from mating between polyploids and diploids have reduced fertility
Autopolyploid
is a species with multiple sets of chromosomes derived from different species
can successfully mate with each other, but cannot interbreed with either parent species
Allopolyploid
Can drive sympatric Speciation
Sexual Selection
Can also result from the appearance of new ecological niches
Sympatric Selection
Is a region in which members of different species mate and produce hybrids
can occur in a single band where adjacent species meet
Hybrid Zone
What are the three alternative outcomes when hybrids do not become reproductively isolated from their parent species?
Reinforcement, Fusion, Stability
Describes these periods of apparent stasis punctuated by sudden change
Punctuated Equilibria
“The interval between speciation events can range from _________ years (some cichlids) to _______ million years (some beetles), with an average of _______ million years”
4000, 40, 6.5
Depending on the species in question, speciation might require change in a?
Single or Many Genes
Is the cumulative effect of many speciation and extinction events
Macroevolution
