Evolution 1 & Evolution 2 Flashcards
Define evolution
genetic change in a population over generations
difference between small and large scale evolution
small occurs from one generation to the next
large is descent of diff. species from com. ancestor over many gens
What are the three levels of debate and their meaning
- fact- do pops change over time?
- course- what course did it take?
- mechanism- what causes evolutionary change?
Carolus Linneaus theorised what? explain
Fact: Fixity of species
- no evolution, created as seen today
What are the three levels debated by Lamarck
Fact: change of species
Course: scale naturae
Mech: inheritance of acquired characteristcs
Explain Lamarcks inheritence of acquired characteristics
o Environment change > developing new needs to meet new demands
Needs altered animals’ metabolism to change physiology + new traits passed onto offspring
What did Sir Charles Lyell describe? and explain
- Principal of Uniformitarianism
o Laws of physics and chemistry not changed
o Same geological events of pasts seen today
Darwins first three observations?
- able to reproduce > enables growth of pop.
- pops stay same size
- nat. resources are limited
what inference did the first three observations of darwin create
Inference 1: struggle for existence
Darwins 4 and 5th observation
- variation occurs
5. variation is inheritable
what did inference 1, observations 4 and 5 produce of darwin
inference 3: organisms show differential survival + reproduction, favouring advantageous traits = nat selec
explain inference 3 of darwin
nat selection, acting over many gens, produces new adaptions and new species
explain the mechanism natural selection
♣ Individuals w/ more favourable traits would fare better than competitors > survive + pass on traits
what are the three things evolution by natural selection requires
- variation
- differential reproduction
- heredity
what are the three levels of debate theorised by darwin
- Fact: Populations of a species changes over time
- Course: descent with modification
- Mechanism: Natural selection
what were three challenges faced by darwin
- Competing theories
- Time (current theory did not fit estimated timeline of Earth)
- Inheritance (unknown exact course of inheritance)
why does blending inheritence not go with darwins theory
if black flower was advantageous= lose trait
define population
a group within a species of interbreeding individuals and their offspring in the same geographic location
define gene pool
all genes in the eggs and sperm in a population
does natural selection act on the pheno or genotype
pheno
how do new traits arise?
mutation
define mutation
♣ spontaneous error in DNA replication leading to a heritable change in an individual’s genome
♣ Not a ‘change in genetic code’
what two things determine fitness
survival + reproductive success
define adaption
anatomical structure, physiological process, or behavioural trait that evolved by natural selection and improves a organisms ability to survive and leave descendants
two types of selection pressures
♣ Biotic factors (related to another organism- own or another species i.e. competition)
♣ Abiotic factors (relate to environment i.e. topography)
what are the 3 types of selection
natural selection, articifial, sexual
what are the three types of natural selection
a. Stabilising selection: selects against extreme phenotypes (loses extremes, = more narrow, mean remain same)
b. Directional selection: phenotypic character shifts in one direction (pushes range as selects against one phenotype)
c. Disruption selection: selects against average phenotypes (average of range= lower fitness than extremes- bimodal distribution= can result in two species)
define sexual selection
- Selection of trait that give individual an advantage in attracting mates (even if harmful to survival), increase reproductive success
what are the types of sexual selection
♣ Intresexual: ‘Power to conquer:’ outcompeting other males
♣ Intersexual: ‘Power to charm:’ competing to attract female
how can a trait decrease survival chances
trait uses up energy/ visibility to predators
explain when fitness enables a trait to decrease survival chances
o Fitness consists of survival + fertility. If the in fertility (through the ability to attract multiple mates) outweighs the in survival, then fitness overall is
4 steps of speciation
- variation
- isolation
- selection
- speciation
define gradualism
Large differences in anatomical traits that characterise species originate through accumulation of many small incremental changes over long periods of time
define punctuated equilibrium
Long periods of evolutionary stasis (no change) followed by relatively short periods of rapid evolutionary change
