Chapter 2 And 5 Flashcards
immutability
Stasis, lack of change.
taxonomy
The science of biological classification.
binomial nomenclature
Linnean naming system for all organisms, consisting of a genus and species label.
taxon
taxon A group of organisms assigned to a particularr category
theory of inheritance of acquired characteristics
Discredited theory of evolutionary change proposing that changes that occur during the lifetime of an individual, through use or disuse, can be passed on to the next generation.
biogeography
The distribution of animals and plants on Earth.
adaptive radiation
The diversification of one founding species into multiple species and niches.
Darwin’s finches are a classic example of adaptive radiation. An original finch species was brought to the Galapagos Islands from the mainland and, with diversity in beak structure, was able to colonize many different niches on the island. Through adaptive radiation, many different finch species evolved.
natural selection
Differential reproductive success over multiple generations.
population
An interbreeding group of organisms.
mutation
An alteration in the DNA that may or may not alter the function of a cell. If it occurs in a gamete, it may be passed from one generation to the next
Fitness
Reproductive success
directional selection
Natural selection that drives evolutionary change by selecting for greater or lesser frequency of a given trait in a population.
stabilizing selection
Selection that maintains a certain phenotype by selecting against deviations from it.
stabilizing selection
Selection that maintains a certain phenotype by selecting against deviations from it.
gene flow
Movement of genes between populations.
Examples of this include a bee carrying pollen from one flower population to another, or a caribou from one herd mating with members of another herd
genetic drift
Random changes in gene fre-quency in a population.
founder effect
A component of genetic drift the-ory, stating that new populations that become isolated from the parent population carry only the genetic variation of the founders
genetic bottleneck
Temporary dramatic reduction in size of a population or species.
sexual selection
Differential reproductive success within one sex of any species.
sexual dimorphism
Difference in size, shape, or color between the sexes.
reproductive variance
A measure of variation from the mean of a population in the reproductive potential of one sex compared with the other.
For example, in many species of polyandrous elephant seals, females usually have at least one pup in their lifetime, while the majority of male elephant seals father zero pups in their lifetime, while a small number of alpha-male seals father the majority of offspring
systematics
Branch of biology that describes patterns of organismal variation.
homology
Similarity of traits resulting from shared ancestry.
analogous
Having similar traits due to similar use, not due to shared ancestry.
convergent (parallel) evolution
Similar form or function brought about by natural selection under similar environments rather than shared ancestry.
cladogram
Branching diagram showing evolved relationships among members of a lineage.
species
An interbreeding group of animals or plants that are reproductively isolated through anatomy, ecology, behavior, or geographic distribu-tion from all other such groups.
speciation
Formation of one or more new species via reproductive isolation
biological species concept
Defines species as interbreeding populations reproductively iso-lated from other such populations.
reproductive isolating mechanism (RIM)
Any factor—behavioral, ecological, or anatomical—that prevents a male and female of two different species from hybridizing.
Reproductive Isolating Mechanisms If species are reproductively isolated from other species, then what factors keep spe-cies apart? Such mechanisms can be sorted into two categories: premating isolating mechanisms and postmating isolating mechanisms (Table 5.2). Such reproductive isolating mechanisms (rims) have been built into the phenotypes of animals to prevent them from accidentally mating with members of another, similar species. Such a mistaken hybrid mating in most cases would be a wasted reproductive effort, and natural selection promotes mechanisms to prevent such matings. Although premating and postmating barriers to accidental cross-species breeding have evolved, premating barriers are prevalent because they prevent lost mating efforts and prevent wasting of sperm and eggs.
How Species Are Formed
anagenesis
Evolution of a trait or a species into another over a period of time.
cladogenesis
Evolution through the branching of a species or a lineage.
allopatric speciation
Speciation occurring via geographic isolation.
parapatric speciation
Speciation occurring when two populations have continuous distributions and some phenotypes in that distribution are more favorable than others.
gradualism
Darwinian view of slow, incremen-tal evolutionary change.
macroevolution
Large-scale evolutionary change over a long time period or evolu-tion of major phenotypic changes over relatively short time periods.
punctuated equilibrium
Model of evolution characterized by rapid bursts of change, followed by long periods of stasis.
adaptationism
A premise that all aspects of an organism have been molded by natural selection to a form optimal for enhancing reproductive success.
reductionism
Paradigm that an organism is the sum of many evolved parts and that organisms can best be under-stood through an adaptationist approach.
null hypothesis
The starting assumption for scientific inquiry that one’s research results occur by random chance. One’s hypothesis must challenge this initial assumption.
Hardy–Weinberg equilibrium
The theoretical distribution of alleles in a given population in the absence of evolution, expressed as a mathematical equation.
group selection
Notion, largely discredited by the rise of Darwinian theory, propos-ing that animals act for the good of their social group or of their species.
kin selection
Principle that animals behave pref-erentially toward their genetic kin; formulated by William Hamilton.
inclusive fitness
Reproductive success of an organ-ism plus the fitness of its close kin
- John Ray
early scientist- genus species. The species concept.
- Linnaeus- took the species and genus concept and expanded it to express the relationship between all living organisms. He believed in fixity of species but then came up with taxonomy and nominal nomenclature- he gave us the name homo sapiens.
- George Buffon-
species adapt slightly to new conditions. Didn’t believe in evolution that one species could transmuted into others. Related on some biological relationship between humans and apes- Was condemned for saying the earth was 75 k years old.
- Fundamental premises of natural selection: (6)
o More offspring are produced by a species than can be supported by naturally available food sources. This is not the case with humans- as we increased food production and medical knowledge we have overcome most natural checks on population control.
o Within any population or species there exists a significant amount of biological/genetic variability- different in size, fur, eyesight, color etc. Humans have less variation compared to other animals. This premise is important!
o Individuals with advantageous traits will have a edge over other members of their species and live longer. E.g. Be able to outrun predators, you will tend to survive, better eyesight, get more food, live longer. Markings that blend into environment avoid being eaten and hunt better.
o Those individuals with traits that increase their chance of living longer are more likely to reach the age at which they will reproduce and will contribute offspring to subsequent generations and pass down the traits that allowed them to survive. As the environment changes, different traits become more advantageous.
o The traits that are advantageous under current environmental conditions will be passed on. These traits that provided adaptive advantages become more common. If the environment changes then perhaps another animal will survive better- think gold tiger vs white tiger. An individual’s reproductive success is dictated by their reproductive potential or fitness- products of their ability to adapt- or not to specific environmental conditions.
o Over long periods of time, accumulated changes within a species will eventually result in a new species. This is called speciation. Diversion evolution- over a long period of time. Starting with subspecies that eventually separate into separate species. If the diversion continues and entire different genera will come to be. Often aided by geographic isolation. E.g. Trinidad guppies- upstream habitat vs downstream habitat ( deeper, warmer, slow moving- but has a predator) guppies are under pressure to reproduce fast. They have evolved specific characteristics- grow to adults faster than upstream guppies, females have twice as many babies, and are much smaller since size doesn’t matter, more speed does. After 6 years of these guppies being put into an upstream environment, they evolved to reproduce slower and became bigger!
- Misconception of evolution
evolution does not move in a directional or linear matter- there is no specific goal. Just a slight remodelling of their ancestors.
- Micro vs Macro evolution
Microevolution- can result in sub species- shorter spans of time, minimal genetic change, can interbreed
* Macro- over a longer period of time, species diverge- cannot interbreed.
- How does speciation occur in the macroevolutionary scale?
Was thought that macroevolution was the product of lots of microevolution- that they would stop interbreeding and diverge from each other- Phyletic gradualism- but this is not how evolution seems to have happened when we examine the fossil record. Fossil record is incomplete since they cannot really be preserved that well. According to the fossil record it seems abrupt- but its likely a very long period of change.
- Punctuated equilibrium-
that there was a slow evolution and then there was a sudden change in species forms- what we tend to see in the fossil record- but the fossil record is incomplete- tis a probability thing.
- Replacement evolution vs divergent evolution:
Replacement: major climate change- fox evolves into new form that is better adapted to environment- old species is extinct now- this is rare- also called anagenesis- in contained environments.
* Divergent evolution- separate populations spread across large regions. Cladogenesis- much more common where species are separate and somewhat isolated breeding populations.
