Natural Selection/ Speciation Quiz

What is a species?

population whose members can interbreed & produce viable, fertile offspring

Allopatric speciation 

means species are geographically isolated

Sympatric speciation

is when species live in the same area but are reproductively isolated

Geographic Isolation is

is when species are in a different area

 

is a form of allopatric speciation

 

a pre-zygotic barrier

Ecological Isolation is

hardly ever encounter each other

species are in a different habitat

species are in the same region

Temporal Isolation

relates to time

species breed at different times of day

species breed at different seasons or years

is sympatric speciation

Behavioral Isolation

species won't breed because they behave differntly

Some species have specific breeding rituals that are different from others

is sympatric speciation

is reproductive isolation

Mechanical Isolation

species cannot physically mate

 

is reproductive isolation

 

sex organs may not match or "fit"

Gametic Isolation

sperm and egg are not chemically compatible

sometimes the sperm cannot penetrate the egg

sympatric speciation

Post- zygotic barriers: When two different species reproduce and their offspring development are impaired

reduced hybrid viability

Post zygotic barrier: When different species produce an offspring but they are infertile. 

reduced hybrid fertility

Post zygotic barrier: Hybrids may be fertile & viable in first generation, but when they mate offspring are feeble or sterile

hybrid breakdown

gradual divergence over long spans of time, assume that big changes occur as the accumulation of many small ones- is known as

gradualism

 

rapid bursts of change
long periods of little or no change
species undergo rapid change when they 1st  bud from parent population

is known as

punctuated equilibrium

Lamark’s background:

evolutionary biologist - organism adapted to the environment by acquiring traits (changing over time) 

lamark ideas:

• Disuse: organism lost part due to not using them ex: missing eyes & digestive system of the tapeworm 

• Perfection with use & need: organs being used constant results in increasing size like muscles of a blacksmith or large ear of a night-flying bat 

• Hypothesis: he believed that transmit acquired characteristics to next generation (if you broke your arm during pregnancy your child would too- inherited it) 

• He believed "giraffes stretch neck for vegetation and REQUIRED to other offspring

Charles Darwin

he proposed that evolution by natural selection & collected clear evidence to support ideas: British naturalist

Charles Darwin ideas

• Proposed an ancestral species and that other birds diverged (descendant species) 

• Correlation to food source: Seed eaters, Flower eaters, insect eaters Adaptive radiation 

• Rapid speciation: new species filling new niches, bec they inherited successful adaptions 

• Conclusions: small population of original South Amer. finches landed on island 

• Variation: in beaks enabled individuals to gather food successfully in the different environments - that population would change anatomically & behaviorally 

• Accumulation of advantageous traits in population - emerge of different species

What factors seem to drive natural selection.

• Successfully compete- food,shelter and their own territory 

• Successfully feed: obtaining enough food or energy to even survive 

• Successfully reproduce and pass down traits to their offspring 

• Survival of the fit/best fit can survive for food, reproduce, reproductive rights and traits to their offspring 

Summarize Darwin’s findings and ideas about natural selection

1. In natural population variation existed 

2. Overproducing offsprings allow each species to possibly survive to maturity

3. Created competition due to struggling to exist 

4. The other snuggle was characteristics beneficial to become more common in populations and evolving characteristics and change others average ones called: Adaptations 

5. Overall lead to Emergence of new species of a new variation into the environment population

evidence for evolution:

Fossil record : transition species - Layers of sedimentary rock contain fossils, show record over time and succession through periods 

evidence for evolution: Anatomical record

• homeologous & vestigial structures + embryology & development 

• Homologous structure: same similarities in character result due to common ancestry 

• They have similar structure, similar development, different functions, evidence close evolutionary relationships 

Analogous structures evidence for evolution:

• Similar functions, external form, different internal structures & development 

• Different origin and no evolutionary relationships 

Convergent evolution: evolved in 3 separate animal groups as similar solutions to similar problems 

unrelated species independently developing similar traits in response to similar environments or ecological challenges 

• fish : aquatic vertebrates 

• Dolphins: aquatic mammals (similar adaptations to life in the sea not closely related) 

Parallel Evolution:

• common niches filling similar ecological roles in similar environments but not closely related

  • Ex: marsupial and placental mammals. 

Vestigial organs:

•  having structures that serve lil or no function- deleterious mutations accumulate in genes for non critical structures w/o reducing fitness 

Artificial selection:

human-caused evolution

Somatic Cell-

body cell, contains 2 sets of

chromosomes- Diploid

Gamete-

sex cell (sperm and egg) contains one set of

chromosomes- haploid

Autosomes-

chromosomes that do not determine

gender (pairs 1-23 in humans)

Sex chromosomes=

determine gender (pair 23 XY in

humans)

Gregor Mendel-

• carried out experiments on pea

plants

• Studied many traits of peas

Traits = characteristics (pod shape, pea shape, flower

color)

Alleles-

different versions of genes

EX: the gene for flower color can be purple or white.

Dominant-

the expressed form of the trait.

Represented by a capitol letter (P)

• Only 1 allele that is dominant is needed to be

  expressed

Recessive-

the trait that is not expressed when the

dominant allele is present.

• Represented by a lowercase letter (p)

• Must have 2 copies in order to be expressed

Homozygous-

if 2 alleles of a particular gene are the

same. (PP or pp) 

Heterozygous-

2 alleles of a particular gene are

different. (Pp)

Genotype-

genetic make up (letters PP or pp)

Phenotype-

physical appearance or characteristics.

(purple or white flowers)

Law of Segregation-

There is always a ½ (50%)

chance you will get on allele or the other.

Law of Independent Assortment-

traits will not affect each other (only applies to genes that aren’t

linked)

What are the post reproduction barriers?

• Prevent hybrid offspring from developing into a viable, fertile adult 

• Reduced hybrid visibility : genes of different parent species can interact + impair the hybrid development 

• Reduced hybrid fertility : they may be sterile and different number of chromosomes,structure + meiosis in hybrid that fial to produce normal gametes 

Ex: horses (64 chromosomes)  vs donkey (62 chromosomes) = mule, vigorous but sterile 

• Hybrid breakdown: may be fertile + viable in first generation but mate offspring are feeble or sterile - not help persistent populations 

• Some organisms can offspring but infertile

Differentiate between gradualism and punctuated equilibrium

Charles Darwin + Charles Lyell 

is small change over a long time 

• Assumed big chances occur as the accumulation of many small ones 

Stephen Jay Gould + Niles Eldredge 

• Rapid burst of change mixed with log periods of little or no change 

• Periods long  of little or no change 

• Species undergo rapid change when they 1st bud form parent population 

Stabilizing selection

individuals with average or intermidate traits are favored

• ex: humans babies born with very low brith or very high have higher mortality, while average sized babies survive more often

Directional selection

favors one extreme variation

• ex: birds with large, strong beaks are more successful at eating so beak size increase in population

Disruptive selection:

favors both extreme phenotypes in a population 

• ex: small salmon sneak into nesting area to fertilize eggs  while large salmon fight for dominanc, medium sized salmon are less successful at either