Bio 142 exam 2 part 1/5
Ecological Reproductive Barrier
Individuals in different species in the same community fail to encounter each other due to habitat isolation
Habitat Isolation
Breed in different locations
Behavioral Reproductive Barrier
Individuals in different species fail to recognize each other as suitable mates
Mechanical Reproductive Barrier
Structural diffferences prevent mating
Postmating Prezygotic
Despite mating, gametes of different species don't undergo successful fertilization
Gametic Incompatibility
Sperm of one species can't fertilize the egg of another species.
Conspecific Gamete Precedence
Sperm of conspecifics outcompetes sperm of heterospecifics.
Postzygotic
Despite mating and fertilization, different species produce less fit hybrids.
Hybrid Inviability
Hybrids dont survive well within species offspring.
Hybrid Sterility
Hybrids are less fertile than within species offspring so they dont produce functional gametes.
Biological Species Concept
groups of individuals that can interbreed and produce viable and fertile offspring
Biological Species Concept Weaknesses
Cannot accommodate asexual organisms, Cannot elucidate fossil species, Many “good” species hybridize
Morphological Species Concept
A group of individuals that look more like each other than like any other individuals.
Morphological Species Concept Strengths
Can accommodate asexual organisms, Can elucidate fossil species, Morphologically distinct suggests limited gene flow;
evolutionary independence.
Morphological Species Concept Weaknesses
Would split up sexually dimorphic species, would combine indistinguishable species, features used to identify species are random.
Phylogenetic Species Concept
A monophyletic group of individuals that share uniquely evolved "derived" traits.
Monophyletic group
Includes an ancestral population and all of its descendants but no others on a phylogenetic tree.
Phylogenetic species concept strengths
can be applied to any population, logical: groups can only have synapomorphies if they are evolutionary independent
Phylogenetic Species Concept Weaknesses
Requires extensive genetic data, may result in many microspecies.
Unified Species Concept
use data from morphology, DNA, reproduction, behavior, geography, ecology, etc
Unified Species Concept Strengths
Incorporates multiple factors, making it applicable to various scenarios.
Unified species concept Weaknesses
Can be complex to apply, and defining precise criteria may be challenging
Cases supporting/ruling out biological species concept
supported when reproductive isolation is clear, but its challenged by hybridization in some cases
Cases supporting/ruling out morphological species concept
useful for fossils and visually distinct organisms but may fail with cryptic species
Cases supporting/ruling out phylogenetic species concept
Supported by molecular data, especially in cases where morphology is misleading.
Cases supporting/ruling out unified species concept
useful in complex situations where multiple criteria is needed, such as cryptic species with both genetic and ecological differences.