Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
Speciation
|
The origin of new species, is at the focal point of evolutionary theory
-evolutionary theory must explain how new species originate and how populations evolve |
|
Microevolution
|
consists of changes over time in allele frequency in a population. Manifested in adaptations that evolve within a population, confined to one gene pool
|
|
Macroevolution
|
refers to evolutionary change above the species level. Grand scale/ longer time
|
|
Prokaryotes vs Eukaryotes
|
Prokaryotes- bacteria, aquatic, 1st organisms
Eukaryotes- Protists(ameoba) - fungi- plants- animals |
|
The Biological Species Concept
|
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 other populations
Gene flow between populations holds the phenotype of a population together(rep. isolation) |
|
Reproductive Isolation
|
the existence of biological factors(barriers) that impede two species from producing viable, fertile, offspring.
- can be classified by whether factors that stop members of 2 species from producing offspring act before or after fertilization |
|
Hybrid
|
offspring of crosses between different species
|
|
Prezygotic Barriers
|
block fertilization from occurring by
-stopping different species from attempting to mate -preventing the successful completion of mating -hindering fertilization if mating is successful |
|
Habitat Isolation
|
Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers.
|
|
Temporal Isolation
|
Species that breed at different times of the day, different seasons, or different years cannot mix their gametes.
|
|
Behavioral Isolation
|
Courtship rituals and other behaviors unique to a species are effective barriers
|
|
Mechanical Isolation
|
Morphological differences can prevent successful mating. Snails with shells spiraling in opposite directions
|
|
Gametic isolation
|
Sperm of one species may not be able to fertilize eggs of another species
- because proteins on the surfaces of the egg and sperm cannot bind to each other -red / purple sea urchins |
|
Postzygotic Barriers
|
after fertilization
prevent the hybrid zygote from developed into a viable fertile adult -reduced hybrid viability/fertility -hybrid breakdown |
|
Reduced hybrid viability
|
Genes of the different parent species may interact and impair the hybrid's development
|
|
Reduced hybrid fertility
|
Even if hybrids are vigorous, they may be sterile
|
|
Hybrid breakdown
|
Some 1st generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile
|
|
Limitations of the Biological Species Concept
|
very hard to define species
cannot be applied to fossils or asexual organisms(including prokaryotes) -only for organisms w sexual reproduction |
|
Morphological species concept
|
defines species by structural features
- applies to sexual and asexual species but relies on subjective criteria - researchers may disagree on which features distinguish a species (limitation) |
|
morphological
|
shape/appearance
organisms that are similar belong to same species |
|
Ecological Species Concept
|
Views a species in terms of its ecological niche( the role it plays & resources it uses in the specific environments in which it is found)
-applies to sexual/asexual species and emphasizes the role of disruptive selection as organisms adapt to different environmental conditions |
|
niche
|
the role it plays & resources it uses in the specific environments in which it is found
Ecological- niche- Amphibians 2 species may appear similar but eat differently and may survive in different temperatures(have different niches) |
|
Phylogenetic species concept
|
Defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.
a species is the smallest set of organisms that share an ancestor and can be distinguished from other such sets |
|
Phylogeny
|
Ancestry- where organisms descend from
|
|
What is distinct about phylogenetic species?
|
distinct morphology or molecular sequences
- applies to sexual/asexual species -can be difficult to determine the degree of difference required for separate species |