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30 Cards in this Set

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Formation of a new species
unbranched lineage, when a species changes so drastically over time that it becomes a different species and the anchestor ceases to exsit.
branched lineage, when 1 or more new species devolops from an anchestral species, but the ancestor cont. to exist, (Only cladogenesis can promote biological diversity by increasing the number of species.)
Biological species concept
(Mayr 1942) Species are groups of actually or potentially interbreeding populations, which are reproductivly isoloated from other such groups. defines a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are unable to produce viable, fertile offspring with members of other populations
Biological species concept EX.
A businesswoman in Manhattan may be unlikely to meet a dairy farmer in Mongolia, but if the two should happen to get together, they could have viable babies that develop into fertile adults
reproductive isolation (Isolation Factors)
The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids. (Maintains Integrety of purety of species)
Prezygotic Isolating factors (Barriers)(“before the zygote”)
impede mating between species or hinder the fertilization of ova if members of different species attempt to mate.
Postzygotic Isolating factors (barriers) (“after the zygote”)
often prevent the hybrid zygote from developing into a viable, fertile adult.
Limitations of the Biological Species Concept
the number of species to which this concept can be usefully applied is limited. For example, there is no way to evaluate the reproductive isolation of fossils or asexual organisms such as prokaryotes.
morphological species concept
a group of organisms that differ in some anatomical respect from all other groups. characterizes a species by its body shape, size, and other structural features.
Limitations morphological species concept
Gray tree frog - Hyla versicolor and Hyla chrysocelis = look the same but have different calls (One disadvantage, however, is that this definition relies on subjective criteria; researchers may disagree on which structural features distinguish a species.)
paleontological species concept
focuses on morphologically discrete species known only from the fossil record. We are forced to distinguish many species in this way because there is little or no information about their mating capability.
ecological species concept
views a species in terms of its ecological niche, its role in a biological community. For example, two species of Galápagos finches may be similar in appearance but distinguishable based on what they eat. Unlike the biological species concept, this definition can accommodate asexual as well as sexual species.
phylogenetic species concept
defines a species as a set of organisms with a unique genetic history—that is, as one branch on the tree of life. Biologists trace the phylogenetic history of a species by comparing its physical characteristics or its molecular sequences with those of other organisms
sibling species
species that appear so similar that they cannot be distinguished on morphological grounds
Two bird species in a forest are not known to interbreed. One species feeds and mates in the treetops and the other on the ground. But in captivity, the two species can interbreed and produce viable, fertile offspring. What type of reproductive barrier most likely keeps these species separate? Explain.
Since the birds are known to breed successfully in captivity, the reproductive barrier in nature must be prezygotic. Given the species differences in habitat preference, the reproductive barrier is most likely to be habitat isolation.
Which species concept can be used for both asexual and sexual species? b. Which can only be applied to sexual species? c. Which would be most useful for identifying species in the field?
All species concepts except the biological species concept can be applied to both asexual and sexual species because they define species on the basis of characteristics other than ability to reproduce. b. The biological species concept can only be applied to extant sexual species. c. The easiest species concept to apply on a field trip would be the morphological species concept because it is based only on the appearance of the organism. Additional information about its ecological habits, evolutionary history, and reproduction are not required.
Habitat or Ecological Isolation Mechanism
When populations live in different areas and don't interact. Ectoparasites, basking turtle, cooters
allopatric speciation
gene flow is interrupted when a population is divided into geographically isolated subpopulations. (Devolpment of a new species as a result of a physical barrier)
EX. Lung Fishes - South Amer., Afr., Australla -3 genera, no gene flow, contential divide cause speciation Ex. - the water level in a lake may subside, resulting in smaller lakes that are home to separated populations
Temporal Isolation
Occurs when mating or flowering takes place at different times of the day or different seasons. Ex. Night Blooming Catus and Day blooming Catus
Behavioral Isolation
different species are not sexually attracted to each other, they might have different courtship rituals and/or displays. Ex. The dancing of flys to atract.
Mechanical Isolation
occurs when structrial differences in genotype or flowers prevent copopulation or pollen transfer. Ex. Size of flower one big one small brid will not fit in one. Ex. Huge dog 4ft and a little dog 12inch is not going to mate even though same species
Gametic Isolation or Physological Isolation
When male and female gametes fail to fuss or cannot survive in the female reproductive tract of another species. Ex. Starfish. Ex pH to low or high
hybrid Inviability
when hybrid zygotes don't devolpe to sexual maturity. Hybrid born alive but dies afterwards. (post zygotic)
Hybrid sterility
when hybrids dotn produce funtional gametes. (post zygotic)
sympatric speciation
speciation takes place in geographically overlapping populations. (Occurs when a sub population is reproductively isolated from its parent population.) Typically how plants evolve
Non disjunction
acident during cell division that results in extra set of chromosome. (
Instantaneous Speciation
by devolpment of polyploidy, or the production of a single indivdual that for varies reasons can't interbreed with members of the species to which parents belong.
Punctuated Equilibrium
(Niles Eldredge, Stephen Jay Gould) fast change, species remain unchanged (stasis) for long periods of time followed by a period of "rapid change"
Darwin vs Punctuated Equilibrium
(Darwin vs Gould,Eldredge)
small chages over a period of time vs stasis then rapid change