Flashcards in Chapter 2 Deck (56)
3 species concepts to consider
**All are necessary for continued survival of species and natural communities
Components of species diversity
origin of species
measuring species diversity
Components of genetic diversity
differences among populations
Components of ecosystem diversity
keystone species and resources
What is included in species diversity?
all species on earth
represent range of evolutionary adaptations to particular environments
provide many plants and animal products that can be used as food, shelter, and medicine.
What are the 2 common definitions of species concepts?
morphological species definition
biological species definition
Species concepts: What is the morphological species definition
a group of individuals that is morphologically or biochemically distinct from other groups
-not helpful with scale
-ex. all birds distinct from mammals and reptiles
Species concepts: what is the biological species definition
a group of individuals that actually or potentially breed among themselves and do not breed with individuals of other groups
What are the issues with the biological species definition?
-operationally difficult to determine
-not generally useful
What are two general problems with trying to classify species?
What are the 5 kingdoms that are generally recognized?
How are species classified, from biggest to smallest classification?
Name two theories of how new species originate.
transformation of species (phyletic evolution= cladogenesis = speciation)
What is adaptive radiation?
the evolution of many species from a single ancestor in response to many different environments
seen and studied on islands
-mammals (s. am.)
Define the transformation of species
multiplication of species via phyletic evolution/cladogenesis/speciation
Can speciation maintain current levels of biodiversity? Why?
rate= higher for extinction than speciation by 1000x
area of habitat = smaller areas prevent speciation.
-less of Earth's surface supports natural communities = less opportunity for speciation and evolution
Why can't speciation of most threatened species maintain the current level of biodiversity?
because many threatened species are the sole remaining representatives of their genus or family.
ex. coelacanth in Indian Ocean
Giant panda in China
extinction of these could not be balance by appearance of new species.
Three ways to measure species diversity
alpha diversity (species richness)
*In practice, these are often correlated.
What is species richness/ alpha diversity?
a way to measure sp. diversity
"the number of species in a community"
ex. a forest in wisconsin vs. the amazon which would have greater # of species
What is gamma diversity
the number of species in a large region (or continent)
includes diverse biological communities or wide geographic areas
What is beta diversity?
variability of sp. composition along environmental or geographical gradients
gamma diversity/ alpha diversity = variability
Define genetic diversity
the genetic variation within species
-among individuals of a single population
-among geographically separate populations
Why is genetic diversity in a gene pool important? (2)
-genetically variable individuals and populations appear to have higher fitness (better survival and reproduction)
-genetic variation is required for evolution in response to a changing environment
Define gene pool
total array of genes and alleles in a population
How do different genetic alleles arise?
from genetic mutation.
alleles are just a different form of a gene
Individuals can be _______ or ________ for a gene.
genotype determines their phenotype
Monomorphic vs. polymorphic populations
a population has either one allele (monomorphic) or multiple alleles (polymorphic) for a trait
ex. a tribe has only the allele for blonde hair.
What is the cause of genetic differences among populations?
Populations often differ genetically
-esp. in widespread sp. that have a broad environmental range
-some of the genetic differences may be adaptive and caused by selection
(others may not be adaptive & caused by genetic drift)
Selection of an allele vs. genetic drift
selection: differential survival and reproduction of different genotypes
genetic drift: random fluctuations of allele frequencies. not necessarily a good thing. Happens with small populations.