E5 - Types of Evolution Flashcards
species
all members of a population who can breed with one another under natural conditions
-AND whose offspring can do the same
TRUE IR FALSE:species continuously evolve
TRUE
When evolution leads to the evolution of an entirely new species, we call this….
speciation
Reproductive Isolation
For a new species to form, individuals from the original species must evolve to become reproductively isolated from the remainder of the population
This would also involve a new independent population that can breed with one another
reproductive isolating mechanism
any factor which prevents two populations from interbreeding while in the same region
What is one way for a species to split into 2
-populations to seperate geographically
-changes in the sae trait keep speicies reproductivel isolated
ex. if lizard were in hot enviroment their dewlaps would change ti red
-males left with yellow dewlaps would not be recognzied by femakes, therefore reproductively isolated
Reproductive Isolating Mechanism: Prezygotic
Reproductive isolating mechanisms may be classified as a prezygotic mechanism
-are mechanisms that prevent fertilization and zygote formation
Reproductive Isolating Mechanism: Prezygotic: Behavioral isolation
- using diff courtships
Reproductive Isolating Mechanism: Prezygotic: temporal isolation
diff species breed at diff times of year
Reproductive Isolating Mechanism: Prezygotic: ecological isolation
similiar species occupy diff habitats within a reigon
Reproductive Isolating Mechanism: Prezygotic: mechanical isolation
diff features lead to incompatability
Reproductive Isolating Mechanism: Prezygotic: gamte isolation
male gamete may not recognize and fertilze egg
Reproductive Isolating Mechanism: Postzygotic
Reproductive isolating mechanisms may be classified as a postzygotic mechanism
-are mechanisms that prevent a fertilized egg from growing into a viable adult
**Viable means capable of sustaining life
Reproductive Isolating Mechanism: Postzygotic: zygotic mortality
-mating possible but gentic diff may cause zygote to not form properly
Reproductive Isolating Mechanism: Postzygotic: hybrid inviabvility
hybrid indivdual devleopes but dies before birth or dies before maturing
Reproductive Isolating Mechanism: Postzygotic: hybrid infertility
hybrid offspring is healhty, viable and seryile
i.e donkey can nto produce more donkey offsprings
Modes of Speciation: Allopatric Speciation
Most new species form when a single species is separating into two geographically isolated populations
-This is called allopatric speciation
Once populations are physically separated, they cannot exchange genetic information so are reproductively isolated
They will respond to their environment and will become less and less similar over time.
Modes of Speciation: Sympatric Speciation
Sympatric Speciation: A new species can also evolve from within a large population
-No geographic isolation is necessary
This can happen gradually, as a response to a change in the environment, or suddenly through a random mutation (the key here is that there is a reduction in gene flow between the populations)
Both species will inhabit the same geographic area but are genetically incompatible
Types of Evolution: Adaptive Radiation
-Adaptive radiation occurs when a single species evolves into a number of distinct but closely related species (each new species fills a different niche)
-most commonly occurs when a variety of new resources become available that are not being used by other species
- ex. darwins finches
Types of Evolution: Divergent Evolution
-Divergent evolution is when a group/closely related groups (that share a common ancestor) are placed under selective pressures and therefore evolve to occupy unique niches (this is due to the development of differences over time)
SIMPLIFED: TWO OR MORE SPECIES DIVERGE FROM A COMMON ANCESTOR EX. WOLLY MAMMOTH AND ELPHANT
- allowed us to develop such great biodiversity of life
-This is because all natural ecosystems require a number of species each with unique ecological roles
For example, we need producers, consumers, decomposers, and scavengers to maintain balance with the ecosystem (these roles are NEVER filled by a single species)
TRUE OR FALSE: WE HAVE EVOLUTION EVEN WITHOUT NATURAL SECTION
FALSE
- WE MUST HAVE NATURAL SELECTION IN ORDER FOR EVOLUTION TO OCCUR
Types of Evolution: Convergent Evolution
Convergent evolution occurs when two different species or taxa evolve to occupy similar ecological niches
SIMPLIFED: 2 OR MORE DISTINCT SPECIES SHARE TRAITS NOT DUE TO A COMMON ANCESTOR I.E BUTTERFLIES, BATS, BIRDS, ALL HAVE NO COMMON ANCESTOR WITH WINGS
Similar adaptations may be favoured in very different geographic regions that have very similar selection pressures
Types of Evolution: Coevolution
-Coevolution is when a species’ evolutionary success is closely linked to that of another species
-For example, certain plants have evolved hard protective shells to protect their seeds while birds also developed stronger jaws and teeth for chewing through those same hard shells
In some extreme cases, species can become so closely dependent that the extinction of one species could lead to the extinction of the other
Symbiotic relationships are good examples of coevolution
TRUE OR FALSE: ISOLATION CAN GIVE RISE TO SPECIATON
TRUE
TRUE OR FALSE: ISOLATION IS A MECHNASIM FOR CHANGE OVER TIME
FALSE
IT IS NOT A MECHANISM FOR CHANGE OVER TIME
-HOWEVER IT CAB REDUCE GENE FLOW
TRUE OR FLASE; CHANGE OVERTIM EWHICH CAN OCCUR IN THE GENE POOL POPULATION CAN BE DUE TO GENTIC DRIFT, NATURAL SECLTION
TRUE
WHAT GROUNDBIRD SURVIVED THE DROUGHT
- THE ONES WITH LARGER BEAKS
–> OFFSPRING GOT THESE BEAKS AS A RESULT OF NATIRAL SELECTION AND TEH TRAIT BEING FAVORED
WHEN DID THE SMALLER BEAKED BIRDS SURVIVE
WHEN THERE WAS MROE WATER
THUS CHANGES LIKE THESE IN THE GALAPAGOS GENERATE DIFF SIZEZ OF BEAKS
-MALES ONLY RESPONDED TO SONGS OF THEIR OWN SPECIES
-APPERENCES ALSO PLAYED A ROLE
HOW DO HUMANS IMPACT SPECICATION?
Many human activities, such as
agricultural expansion and the construction of roads, are causing once large habitats
to be fragmented into smaller areas that eff ectively isolate populations
adaptive radiation
the relatively rapid
evolution of a single species into many
new species, fi lling a variety of formerly
empty ecological niches
