Term
|
Definition
Species
– Is the most basic category of classification
-There is no single species concept that can
explain, define, and classify ALL species
– For example, mules, the fossil record, subspecies
-Multiple ways of thinking about species may help
with this problem |
|
|
Term
|
Definition
Typological
Biological
Phylogenetic
Morphological |
|
|
Term
|
Definition
First developed by Plato
Species are represented
by perfect “archetypes”
Visualized species as nonchanging
and fixed with
common morphology
– Ex: dog breeds |
|
|
Term
|
Definition
| is an original model of a person, ideal example, or a prototype upon which others are copied, patterned, or emulated; a symbol universally recognized by all. |
|
|
Term
| Problems with typological concept |
|
Definition
Species DO change over time, through
evolution
– they are not fixed
Typology alone does not help us EXPLAIN
variation
But we do still see the remnants- each
fossil species often has a “type specimen” |
|
|
Term
|
Definition
Developed by Ernst Mayr
in 1928
– Studied birds in New
Guinea
Natives classified birds in
a similar manner to
Europeans, suggesting
real underlying differences |
|
|
Term
|
Definition
A species is defined as a group of
interbreeding populations
– These populations produce viable and fertile offspring
Reproductive isolation is key for the
development of new species
Works fairly well with what we know about how species come into existence |
|
|
Term
| interbreeding populations |
|
Definition
| Populations that breed with eachother |
|
|
Term
|
Definition
fertile- the natural capability of giving life, can reproduce
viable-can survive |
|
|
Term
|
Definition
| the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences |
|
|
Term
| Types of reproductive isolation |
|
Definition
Premating, prezygotic- occurs before
mating and fertilization:
– Environmental barriers, behavioral
differences, timing of mating
Postmating, postzygotic- occurs after
mating and fertilization, but does not
produce viable offspring:
– infertile hybrids |
|
|
Term
|
Definition
| Factors which cause species to mate with their own kind Temporal isolat.-Individs. of diff species do not mate b/c they mate at diff. times of day or in diff. seasons. Ecological isolat.-Individs mate in their preferred habitat, & therefore do not meet individs of other species w/diff ecological preferences. Behavioral isolat-Potential mates meet, but choose members of their own species. Mechanical isol. -transfer of sperm does not take place. |
|
|
Term
|
Definition
| Genomic incompatibility, hybrid inviability or sterility. Gametic incompatibility. Sperm transfer takes place, but egg is not fertilized. Zygotic mortality. Egg is fertilized, but zygote does not develop. Hybrid inviability. Hybrid embryo forms, but of reduced viability. Hybrid sterility. Hybrid is viable, but resulting adult is sterile. |
|
|
Term
How does speciation occur?
Modes of Speciation |
|
Definition
Four main modes of speciation (mostly
through geographic isolation of different types)
-Allopatric
–Peripatric
–Parapatric
–Sympatric |
|
|
Term
Allopatric
Mode of Speciation |
|
Definition
Geographically isolated populations
developed differences through selection, drift, mutation that eventually produce reproductive isolation
Believed to be most common |
|
|
Term
Peripatric
Mode of Speciation |
|
Definition
isolation of small population from parent population -Essentially, this is the founder effect
Divergence arises from selection,
mutation, and drift
Requires some time as well
– Suggested for some insects, especially
Hawaiian Drosophila (fruit fly) |
|
|
Term
Parapatric
Mode of Speciation |
|
Definition
Neighboring populations share small zones of overlap with some gene flow, but selection on small regional variations produces new species
Mostly selection overcoming modest gene
flow
Some plants and grasses |
|
|
Term
Sympatric
Mode of Speciation |
|
Definition
Reproductive isolation occurs between two species freely interbreeding
Not well understood, and very controversial
Three-spined stickleback- two variants in same lake |
|
|
Term
Gradualism
Speciation Tempo |
|
Definition
Gradualism- Gradual process of
natural selection
-Creates new adaptations
-When sufficiently different leads to new species |
|
|
Term
Punctuated Equilibrium
Speciation Tempo |
|
Definition
Punctuated Equilibrium
-Species remain relatively static for long periods of time
-Followed by rapid changes and speciation events
-Most believe that it is through a combination of these models that speciation occurs |
|
|
Term
| Problems with Biological Species |
|
Definition
-If two populations are geographically
isolated, are they necessarily reproductively isolated? Ring species,
subspecies
-Fossils- We have no idea about reproduction |
|
|
Term
|
Definition
Phylogenetic species are based upon
fixed differences that characterize ancestrally related lineages
Species is the minimally analytical unit; the building block of lineages
Lineages are assumed to be isolated from
gene flow |
|
|
Term
|
Definition
Study of evolutionary relationships
Two patterns used in construction of “trees”
Anagenesis- changes within a species
Cladogenesis- split of one species into two new species; note that ancestral species then ceases to exist! |
|
|
Term
|
Definition
Groups of organisms (taxa) that contain an ancestor and all decedents
Species are defined here as the minimal
monophyletic group. |
|
|
Term
|
Definition
Species must have been evolutionarily independent long enough to have developed features that distinguish them
Ex. Apes are a monophyletic group.
However, chimpanzees share a set of features that distinguish them from all
other apes |
|
|
Term
| Problems with Phylogenetic Species |
|
Definition
What is a diagnostic difference?
This species concept requires some
consensus on phylogeny, or how the “tree” is set up
Hominin/human evolution has little
consensus in this regard! |
|
|
Term
| Morphological Species Concept |
|
Definition
Species are defined as populations with similar morphological characteristics
Useful for the fossil record as we can see morphology
No dependence on genetics, reproduction; rather phenotype
However, each difference seen may result in a new species! |
|
|
Term
|
Definition
| is any observable characteristic or trait of an organism: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior (such as a bird's nest) |
|
|
Term
|
Definition
Morphological differences within a
species! |
|
|
Term
| What works in Paleoanthropology? |
|
Definition
A combination of species concepts towards hypotheses/questions is best determine what it is you are asking
Extant primates provide good evidence on evolutionary relations and morphology that could be used to construct phylogenies
Morphologies that indicate functional differences are also useful; these indicate some change in response to the environment |
|
|
Term
|
Definition
Modern genetics may have some answers- recent advances in DNA analysis, aDNA, mtDNA
More fossils are always good and help us
build a more representative population to help with morphology differences
Archaeology can help |
|
|
