chapter 14 Flashcards
what is speciation & what are the two patterns of speciation
the development of a new species;
**anagenesis–>transformations of an unbranched lineage of organisms, sometimes to state different enough from ancestral population to justify renaming it as a new species
**cladogenesis–>branching evolution, the branching of one or more new species from a parent species which continues to exist [this is more important than anagenesis in history of life— more common and can promote biological diversity by increasing the number of species]
what are the two concepts of a species (the two ways to define a species)
- *morphospecies–>species defined by their anatomical features; most common method for describing species however some difficulties;
- -»sometimes it is difficult to determine if a set of organisms represents multiple species or a single species with extensive phenotypic variation
- -»sometimes two populations morphologically almost indistinguishable may be different species based on other criteria
- -»does not explain how each species remains distinct from other species
- *Biological species –> species defined by the ability to interbreed and produce fertile offspring; reproductive isolation from other species; some limitations are;
- -»cannot be applied to organisms that are completely asexual in their reproduction
- -»cannot be applied to extinct organisms
- -»difficult to apply to two populations which are geographically separated
what are the two categories of isolating mechanisms & what are examples of each
factors that impede tow species from producing fertile offspring thus contributing to reproductive isolation;
**prezogotic–»impede mating between species or hinder fertilization should members of different species attempt to mate –examples; geographic, habitat, seasonal, behavioral, structural, gametic
**postzygotic–»prevent the hybrid zygote from developing into a viable fertile adult, in the event the fertilization does occur – examples: zygote mortality, hybrid inviability, hybrid sterility, hybrid breakdown
what is allopatric speciation & what is an example
geographic separation of species –-this type of speciation occurs when the initial block to gene flow is a geographical barrier that physically isolates the population—-example: adaptive radiation
what is adaptive radiation & what is an example
the spreading out of a population into different environments accompanied by divergent adaptive changes—example: Darwin’s finches
what is sympatric speciation & what is an example
geographic overlap of species— this types of speciation occurs when new species from within the range of the parent population
example: hybridization and polyploidy
what is hybridization and polyploidy & what is an example
autopolyploid–>an organism that results from a single species that doubles its chromosome numbers
allopolyploid–>a polyploidy hybrid resulting from contributions of two different species, this interspecific hybridization
—-example of hybridization and polyploidy; wheat
why was the evolution of photosynthesis important in the evolution of living organisms
divergence of autotrophs from heterotrophs, release of oxygen made respiration more efficient; which lead to development of the ozone layer; invasion of land by early plants
what is an autotrophic organism, what is a heterotrophic organism & which type do we think evolved first
autotrophic–>plants capable of synthesizing its own food from simple organic substances [producers]
heterotrophic–>one utilizing organic compounds to obtain carbon that is essential for growth and development [consumer]
[heterotrophs evolved first]
what is an aerobic organism, what is an anaerobic organism & which type do we think evolved first
aerobic–>organism that requires oxygen gas
anaerobic–>organism that can survive without gas
[anaerobic evolved first]
what is phylogeny
the evolutionary history of a group of organisms, represented by hypothesized ancestor-descendant relationships— phylogenetic trees that trace inferred evolutionary relationships
