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*SPECIES*

GEOGRAPHICAL ISOLATION
example
the Hawaiian Archipelago, which consists of numerous volcanic islands. Each island is physically diverse, allowing for natural selection to occur, which can lead to reproductive isolation. This type of allopatric speciation occured among honeycreepers (type of bird). There are over 20 living species of honeycreepers that all evolved from a single species that had colonized an island. Honeycreepers dispersed to the different islands and evolved. Those that came back to their native island were not capable of interbreeding with the natives anymore because the visiting honeycreepers had adapted to their new environment.
*SPECIES*

How GEOGRAPHICAL SPECIATION
happens?
A geographic barrier arises, isolating the two populations. The newly isolated populations now go through a period of isolation. Some of the individuals within a population might exhibit a trait more suitable for the new environment. This variant allows for differential survivorship and reproduction. Those individuals that carry the trait are more likely to survive in the new environment. Therefore, they will leave more offspring. Gradually, the variant trait will become dominant. Theoretically, this would happen with both of the newly isolated populations resulting in reproductive isolation
GEOGRAPHICAL SPECIATION
What happens if geographical barrier disappears but speciation already occurred
The geographic barrier ends. The two populations now have the opportunity to interbreed again. If the populations do not recognize each other as potential mates or cannot produce fertile offspring, speciation has occurred because the populations are reproductively isolated. The two populations have become two different species. If speciation has not occurred, the populations can still interbreed successfully to produce viable, fertile offspring.
Examples of ALLOPATRIC SPECIATION( which is always due to geographical isolation)
Squirrels at Grand Canyon
Honecreepers birds on different Hawaiian islans
House Mice brought Faroe islans and it became a separate species there
SPECIES
A group of organisms which are capable of exchanging genes within the group but are genetically unable
to exchange genes in nature with other groups.
New species form as a result of geographic isolation.
(e.g., continental drift, different islands)
Populations that are geographically isolated will diverge from one another genetically as a consequence
of:
1) unique mutations
2) natural selection
3) genetic drift
Migration interferes with evolution.
In the absence of migration, genetic differences between populations become so great that the formation
of hybrids becomes impossible.
These biologically isolated populations are new species.
Define SELECTIVE PRESSURES
Factors that determine if organism can survive and reproduce. Selctive pressures can favor on phenotype over another
Define BIOLOGICAL FITNESS
the ability to survive and reproduce, Biological fitness is not the same as physical fitness
DIVERGENT v. CONVERGENT EVOLUTION
DIVERGENT - occurs when different selective pressures act on population
CONVERGENT - same selective pressure acts on two different populations
DIVERGENT EVOLUTION
--produces dissimilarities
--may cause speciation over time
--produces homologous structures - same origin and diff function. Ex. Vertebrae - 4 limbs
CONVERGENT EVOLUTION
--unrelated populations become more similar
--not exactly opposite from divergent evolution because they are not generally similar
--produces ANALOGOUS structures - diff. origin, same function - Ex. Bat wing and flying squirrel
2 TYPES OF ISOLATION OF SPECIES
Geographic and Reproductive
REPRODUCTIVE ISOLATION--6 ways species may be isolated
1) Cogeographic
2) Habitat
3) Time
4) Mechanical
5) Behavioral
6) Gametic Mating
REPRODUCTIVE ISOLATION
--6 ways species may be isolated
1) Cogeographic
1) Cogeographic
Species have different ranges but no physical barriers. ex. Salamanders flickers
REPRODUCTIVE ISOLATION
--6 ways species may be isolated
2) Habitat
2) Habitat
Habitat species in the same range but have different habitat Ex. Upland chorus frogs calls from open positions but southern chorus frogs call from places hidden in grass or debris
REPRODUCTIVE ISOLATION
--6 ways species may be isolated
3) Time
3) Time
-Nocturnal v. diurnal (day v night)
-differnet breeding seasons
Ex. American toad breed early in the season and fowler toad later
*SPECIES*

What happens if geographical barrier disappears but speciation already occurred
The geographic barrier ends. The two populations now have the opportunity to interbreed again. If the populations do not recognize each other as potential mates or cannot produce fertile offspring, speciation has occurred because the populations are reproductively isolated. The two populations have become two different species. If speciation has not occurred, the populations can still interbreed successfully to produce viable, fertile offspring.
*SPECIES*

Examples of ALLOPATRIC SPECIATION( which is always due to geographical isolation)
Squirrels at Grand Canyon
*SPECIES*

What is continuous variation?
a trait that's controlled by several genes and exhibits a variety of phenotypes a genetic phenomenon.
*SPECIES*

What is TAXONOMY?
The classification of animals and plants.
*SPECIES*

REPRODUCTIVE ISOLATION
--6 ways species may be isolated
4) Mechanical
4) Mechanical
Physically dont fit together - more common in plants
REPRODUCTIVE ISOLATION
--6 ways species may be isolated
5) Behavioral
5) Behavioral
different mating rituals
ex. differnet breeding calls, color preferences to choose their type
-more commmon in animals
REPRODUCTIVE ISOLATION
--6 ways species may be isolated
6) Gametic mating
6) Gametica mating occurs but a) viable fertile offspring are not produced
b) sperm never reaches egg
-biologically expensive (wasted gametes) It prevents cross breeding, The offspring is sterile.
SPECIES
VARIATION about
selective pressures will not cause speciation unless there is inherited variation in the species
*SPECIES*

SPECIES VARIATION

TYPES and SOURCES list
TYPES:
1) Discontinuos variation
2) continuous variation
SOURCES:
-Different Genes
-environmentally induced
*SPECIES*

SPECIES VARIATION Types:

DISCONTINUOUS VARIATION
Discontinuous variation - POLYMORPHISM
--2 or more distinct forms of a species
--there are ni intermediates ex. snow goose, red+yellow flickers RR Rr rr
*SPECIES*

POLYMORPHISM is the same as
DISCONTINUOUS VARIATION
*SPECIES*

SPECIES VARIATION Types:

CONTINUOUS VARIATION
--intermediate forms are present
Ex. carnations red+white=pink, most dog species
*SPECIES*

SPECIES VARIATION Sources:
1) DIFFERENT GENES
2) ENVIRONMENTALLY INDUCED
1) DIFFERENT GENES
-mutation
-breeding through sexusal reproduction (recombination)
2) ENVIRONMENTALLY INDUCED
*SPECIES*

NATURAL SELECTION
What must be present to Natural selection to occur?
--Variation must be present in a population for natural selection to occur
*SPECIES*

PROGENY =
OFFSPRING
*SPECIES*

NATURAL SELECTION
HOw biological fitness is determined?
--biological fitness is determined by the relative numbers of the reproducing offspring
*SPECIES*

NATURAL SELECTION general points
--If an organism can survive and reproduce, it will leave its genetic informaiton in the next generation
--Survival of the best adapted
*SPECIES*

NATURAL SELECTION 3 types
1) Stabilizing selection
2) DIrectional selection
3) Disruptive selection
*SPECIES*

NATURAL SELECTION
1) Stabilizing selection
1) Stabilizing selection
--Selects against extermes and for the middle common
--occurs during times of change
*SPECIES*

NATURAL SELECTION
2) Directional Selection
- Selects againt one extreme
- is common
-occurs during the times of change
*SPECIES*

NATURAL SELECTION
3) Disruptive selection
-selecting against the middle and for both extreme
-uncommon
occurs during times of change
-can lead to speciation
*SPECIES*

POLYMORPHISM
many forms
occurence of several distinct forms of a species
Causes: 1) differences in major genes

2) envoronmentally induced
*SPECIES*

TRANSIENT POLYMORPHISM
disadvantageous allele becomes advantageous ex. peppered moth
*SPECIES*

LEVELS OF ORGANIZATION - list only
1 individual organism
2 species
3 population
4 community
5 ecosystems
6 biosphere
*SPECIES*

WHAT IS ECOLOGY
the study of the interations between organisms and their environment
LEVELS OF ORGANIZATION

BIOSPHERE
What three things make up the biosphere? top portion of Earth's crust, all waters, the atmosphere
LEVELS OF ORGANIZATION

ECOSYSTEM
All living organisms and the physical environment on which they depend
*SPECIES*

LEVELS OF ORGANIZATION

COMMUNITY
All the species living close enough to interact with each other
*SPECIES*

LEVELS OF ORGANIZATION

POPULATION
individulas of the same species in the same area that constitute an internbreeding and reproducing group
*SPECIES*

LEVELS OF ORGANIZATION

SPECIES
individulas that able to interbreed and produce viable fertile offspring
*SPECIES*

TAXONOMY

MORPHOLOGICAL SPECIES CONCEPT I
Mor. Sp. concept separated groups by physical differences and appearance
Used by classical taxonomist associated with Carl von Linne
TAXONOMY

MORPHOLOGICAL SPECIES CONCEPT II
Carl von Linne
--type speciments = ideal example of what species should look like
-- species were considered fixed
--variation was exception
*SPECIES*

TAXONOMY

BIOLOGICAL SPECIES CONCEPT I
Based on the ability to interpreed and produce viable fertile offspring
*SPECIES*

TAXONOMY
BIOLOGICAL SPECIES CONCEPT II Charles Darwin and other naturalists
Charles Darwin
--variation is common
--distinction between species is not always clear
--species change over time
--sometimes behavior is used to help classify species
*SPECIES*

TAXONOMY

PROOBLEMS WITH THE SPECIES CONCEPT
--gradual variation over a geogrpahical range (ex. salamanders (cline)
--when the range of 2 species begins to overlap , if they interbreed, they were one allopatric (geograph.) species rathere than different species
TAXONOMY

SYMPATRIC SPECIES
species occupying the same area at the same time
TAXONOMY

ALLOPATRIC SPECIES
species separated by time and Place (can occupy the same area)
*SPECIES*

Founder Effect
Founder Effect occurs when one or a few individuals for a new population. When this happens, only a subset of the possible genetic material present in the larger population can possibly be present in the new, small one. The founder effect is a type of genetic drift because gene frequencies changed by chance alone, and not for an adaptive reason.
*SPECIES*
NATURAL SELECTION
Explain survival of the fittest
Individuals who survive are the ones who are best suited to the environment due to variations
*SPECIES*

MUTATION
randon change in DNS
*SPECIES*

ANALOGOUS STRUCTURE
structures that have different origins but the smae functions due to the same selective pressures
*SPECIES*

HYBRID
Organisms that do not breed in nature but do breed or produce fertile offspring in artificial settins
*SPECIES*

PHENOTYPE
The physical characteristics produced by DNA
*SPECIES*

SELECTIVE PRESSURES
Factors that detemine which indivuduals will survive and reproduce
*SPECIES*

HOMOLOGOUS STRUCTURE
Structures that have a similar origin but diff function (forelimbs of vertebraes)
*SPECIES*

WHy is the species Levels of organization conceptual
Species is human construct that helps to classify things
*SPECIES*
CONTINENTAL DRIFT
Evidence of the the fact that earth crust and mantle moving
maps, fossils, hot spotsm geologic movement (countries fit together)
*SPECIES*

CONVERGENT AND DIVERGENT evolution are not opposites
because in convergent the DNA is different to begin with (species will never become one)
*SPECIES*

Problem with classifying species - example
gradual variation over geographica range within California salamanders