A4.1-evolution and speciation Flashcards
current definition of evolution
the process of cumulative change in the heritable characteristics of a population
things to remember regarding evolution
-not linear
-gradual, continuous, subtle process
-POPULATIONS EVOLVE, not individuals
-no direction
Lamarckism
theory stated; organisms acquired characteristics through their lifetime if needed and then pass them onto their offspring
-theory was disproven
why lamarckism is wrong
-it is rather a slow process
-acquired characteristics of an organism in its lifetime does not affect genetic material
micro and marco evolution
micro= small allele changes in small amount of time
macro=large changes in a group over long period of time
point of evidence for evolution
-RNA/DNA amino acid sequences
-selective breeding
-homology and analogy
-fossil record
-direct observation
RNA/DNA/ amino acid sequence for evidence of evolution
-you can compare nucleic acids and protein data from many organisms to examine evolutionary relationships.
-soft wear can compare differences and similarities of codes, to see how closely related
-all organisms have a single shared genetic code that translates the sequence of nucleotides in a gene into corresponding amino acid chain
pseudogenes
homologous genes that have lost their function
selective breeding as evidence for evolution
breeding domestic animals is good to study changes in heritable characteristic
=breeding members of species with desired traits
-shows that species can change over time due to human intervention and mimics natural selection, where organisms with advantageous traits are more likely to survive.
homologous and analogous structures as evidence for evolution
homologous= same structure, different function, different evolution from similar origin, e.g; pentadactyle limb
is DIVERGENT EVOLUTION= when new species develop traits that differentiate them from their ancestor
analogous= different structure, same function, different evolutionary origins, e.g;wings
is CONVERGENT EVOLUTION= unrelated species develop similar traits when living in similar environments
Vestigial Structures
structures found in an organism that is no longer in use but may have been useful at some point in the organism’s life.
Similarities in Early Development as evidence for evolution
Scientists look at embryos of different organisms and find that many embryos resemble one another.
fossils as evidence for evolution
Layer of rock indicates age of fossil (lower in rock layers = older fossils)
what is speciation
process in which one species splits into two or more species
-increases total number of species on earth
-occurs when gene flow is interrupted
Two types of speciation (allopatric and sympatric)
different rates of speciation
-gradualism= gradual accumulation of small changes over long time
-punctuated equilibrium= rapid bursts of change mixed with long periods of little or no change
types of reproductive isolation
-geographical, temporal and behavioral
ALL result in two populations facing different selective pressures and will change
example of geographical isolation
the convo river that is a physical barrier and prevents two ape populations from interbreeding. North has chimps, south has bonbos
allopatric speciation
physical barrier that divides population
(geographical isolation)
sympatric isolation
speciation occurs without physical barriers
(temporal or behavioral isolation)
temporal=incompatible time frames that prevent reproduction
behavioral=population developing behaviors that isolate them
divergent evolution
-common ancestor
-homologous structures
what is adaptive radiation
-outcome of divergent evolution
-allows closely related species to coexist without competing
-source of biodiversity
courtship behavior preventing hybridization
the behaviors exhibited by animals to attract a mate of the same species
These behaviors are crucial in preventing hybridization,
what is a polyploid organism
SPECIATION EVENT
an “accident” during cell division results in full extra sets of chromosomes
happens when chromosomes duplicate but cell does not divide
-More common in plants
-Triploid (3n), Tetraploid (4n), etc.
ABRUPT SPECIATION
autopolyploid
organism that has more than two complete sets of chromosomes, all of which come from the same species.
allotetraploids
Allotetraploids are organisms that have four sets of chromosomes derived from two different species. This type of polyploidy occurs when two different species hybridize and then undergo chromosome duplication, resulting in an organism with two sets of chromosomes from each of the parent species.
-can only interbreed with other allotetraploids
convergent evolution
independently evolve similar traits as a result of adapting to similar environments or ecological niches.
why analogous structures are not evidence for evolution
Analogous structures indicate that two species have evolved in response to similar selection pressures and do not indicate recent shared ancestry.
