Chapter 2 Flashcards
3 species concepts to consider
species diversity
genetic diversity
ecosystem diversity
**All are necessary for continued survival of species and natural communities
Components of species diversity
species concepts
classications
origin of species
measuring species diversity
Components of genetic diversity
gene pools
differences among populations
Components of ecosystem diversity
physical environments
species interactions
trophic levels
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?
- unambiguous
- operationally difficult to determine
- not generally useful
What are two general problems with trying to classify species?
cryptic biodiversity
hybrids
What are the 5 kingdoms that are generally recognized?
plants animals fungi protists monerans (bacteria)
How are species classified, from biggest to smallest classification?
Kingdom Phylum Class Order Family Genus, species
Name two theories of how new species originate.
transformation of species (phyletic evolution= cladogenesis = speciation)
adaptive radiation
What is adaptive radiation?
the evolution of many species from a single ancestor in response to many different environments
seen and studied on islands
general phenomenon
- marsupials (australia)
- mammals (s. am.)
- flowering plants
Define the transformation of species
multiplication of species via phyletic evolution/cladogenesis/speciation
Can speciation maintain current levels of biodiversity? Why?
no.
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)
gamma diversity
beta diversity
*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.
homozygous
heterozygous
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
Cause:
-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.
Define gene flow
transfer of alleles among populations through migration and mating.
-individuals, seeds, pollen grains
-reduces differences between populations
(which means it opposes genetic drift)
What are the four concepts of evolution?
selection
genetic drift
gene flow
gene pool
i think.
Define ecosystem diversity
variety of ecosystems present in a place or geographic area
-deserts, grasslands, wetlands, and forests
supports proper ecosystem functioning
- provides services such as flood control
- protection from soil erosion
- air and water filtering
What are the physical characteristics of an ecologically diverse environment?
ecosystem diversity/composition
biological community
organisms’ impact on the physical environment
limiting resources
Define biological community
species that occupy a certain place and their interactions
Define ecosystem
community plus physical and chemical features of the environment
-species composition depends on sp. interactions and physical environments
Define limiting resource
any component of the niche that restricts population size
ex. roosting sites, soil nitrogen
- can include successional stage
Define succession
change in the species composition in a biological community
How does the physical environment impact ecosystem diversity?
determines whether a site will be a forest, grassland, desert, wetland, etc.
terrestrial communities: depends primarily on temperature and precipitation
aquatic communities: depends primarily on light and oxygen
How can organisms affect their physical environment on a small scale?
wind speed, humidity, temperature
eg. more humid and constant temperature within a forest because of the plants.
Define species interactions and name its subcatergories
defined in terms of positive and negative effects on participants
mutualism, competition, predation
What is mutualism? (also symbiosis)
interaction in which both species benefit
flowering plants and pollinators
losing one participant can endanger the other
Symbiosis: extreme mutualism in which participants cannot survive without each other (ex. lichen = fungus + alga)
What is competition?
interaction with negative effect for both species
may be a problem with introduced species
What is predation?
interaction with a positive effect on one species and a negative effect on another
may indirectly affect the number of prey species
- keeps density of each low enough to prevent competitive exclusion
- ex. Pisaster (sea star) feeds on 15 sp. of mollusks, prevents one or two sp. from being dominant
Name the trophic levels
primary producers primary consumers secondary consumers tertiary consumers (ETC up to 7 levels) and detritivores
What are primary producers?
photosynthetic species that obtain energy directly from sun to build organic molecules necessary for growth
- higher plants in terrestrial communities
- single cell algae and cyanobacteria (blue-green algae) in aquatic communities
What are primary consumers
herbivores
eat photosynthetic species
only small percentage of energy transferred to herbivore level (about 1/2)
- respiration of photosynthetic species
- much plant material is indigestible
What are secondary consumers?
carnivores, predators
eat herbivores
What are tertiary consumers?
secondary carnivores
eat carnivores
What are detritivores?
species that feed on dead plant and animal tissues and wastes
- decomposers
- break down complex tissue and organic molecules
- release minerals back into environment where can be taken up again by primary producers (nitrates, phosphates)
- usually fungi and bacteria, includes vultures and other scavengers, dung beetles, earthworms
What are parasites, pests, and pathogens in relation to trophic levels?
a subclass of secondary consumers (predators)
protozoa, fungi, bacteria
plants (mistletoe)
animals (tapeworms, mosquitoes)
trophic levels linked through food webs.
What are keystone species?
species that determine the ability of large numbers of other species to persist in the community
Four types of keystone species
top predators that control herbivore populations
-gray wolves
pollinators and seed dispersers
-flying foxes in old world tropics and pacific islands
species that modify physical environments
-beavers, leaf cutter ants
continuous food producers
-fig trees
What happens when a keystone species goes extinct?
an extinction cascade= series of linked extinction events
What happens when we try to restore keystone species?
other species and aspects of the physical environment (soil cover) may already have been lost and are irreplaceable.
What are keystone resources?
resources that are crucial to many species in the community
may occupy only a small portion of a conservation area
What are examples of keystone resources?
salt licks and mineral pools (provide essential minerals)
deep pools in streams and springs
- refuge for fish and aquatic sp. during dry season
- refuge for terrestrial animals as drinking water
hollow tree trunks
-breeding sites for many bird and animal species
