Natural Selection Flashcards
EVOLUTION
a change over time
BIOLOGICAL EVOLUTION
genetic changes in a population that are inherited over generations due to natural selection
MACRO EVOLUTION
the development of new species from earlier life forms over many generations
MICRO EVOLUTION
variation that occurs within a species. small changes originate in the gene pool, resulting in small changes in the genotype which are passed onto offspring
SPECIATION
where a new species develops from existing species over time
FOSSIL RECORD
the accumulation of all listed and known fossils of different ages that have been discovered
CONDITIONS NEEDED TO FOSSILIZE
- rapid burial
- high pressure
- low oxygen
- hard-body
FOSSILS
A fossil is the remains, imprints or traces of an organism usually preserved in rock.
HOMOLOGOUS STRUCTURES
Equivalent structures with the same body plan that perform different functions
ANALOGOUS STRUCTURES
structures that happen to perform the same function but that did not originate from a common ancestor.
MODIFICATION WITHIN A SPECIES
many species changed over millions of years to form the species we know today
BIOGEOGRAPHY
the study of the distribution of existing and extinct plant and animal species in specific regions
GENETICS
- the study of inheritance and heredity
COMPARATIVE BIOCHEMISTRY
- comparing molecular composition of living organisms
- is essentially the same in all orgs, supporting the fact that all life shares a common ancestor.
VESTIGIAL STRUCTURES
structures that, in some organisms, decrease in size over evolutionary time with disuse
COMPARATIVE EMBRYOLOGY
when vertebrate embryos are compared to each other at various early stages of development they show certain similarities
ALL VERTEBRATE EMBRYOS HAVE
- a tail bud
- limb buds
- two-chambered heart
HYPOTHESIS
an informed assumption because it provides a proposed solution to a problem or explanation
THEORY
a well substantiated explanation or hypothesis that makes sense of a natural phenomenon
LAMARCK’S THEORY
- the use or disuse of organs may have an effect on the size of the organ over time
- during their lifetime, organisms acquire changes in characteristics that their offspring inherit
PROCESSES THAT CONTRIBUTE TO VARIATION
- Mutations
- Meiosis (Crossing over; Random arrangement of chromosomes)
- Chance fertilisation
- Mating
REASONS FOR LAMARCK’S REJECTION
- the discovery of modern genetics
- was the first scientist to propose that “something” passed characteristics of parents onto the offspring
DARWIN’S OBSERVATIONS
- individuals of a pop produce more offspring than required to ensure survival
- great deal of variation
- some individuals are better adapted and are more likely to reproduce
- characteristics are transferred from the surviving parents to their offspring
NATURAL SELECTION
the mechanism of evolution where nature selects the fittest individuals for survival
WHAT NATURAL SELECTION REQUIRES
- variation in the pop
- characteristics resp for variation must be hereditary
- more offspring must be produced than necessary
ARTIFICIAL SELECTION
the deliberate breeding of plants and animals for desired characteristics that would not necessarily benefit survival
DIFF BETWEEN ARTIFICIAL AND NATURAL
N - environment acts as selection pressure, A - humans select
N - selected charact are advantageous for survival, A - not necessarily adv
N - maintains variation, A - dec variation
SIMILARITIES BETWEEN NATURAL AND ARTIFICIAL
- variation occurs in a particular pop
- variation is hereditary
- same outcome (pop changes over time)
CONTINUOUS VARIATION
- occurs when there is a range of phenotypes for the same characteristic
- it normally forms a continuous spectrum ranging from one extreme to another
eg. ) height in humans
DISCONTINUOUS VARIATION
when phenotypes fit into separate categories with no intermediate forms
- only a single pair of alleles occurs
eg. ) sex
SPECIES
a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.
POPULATION
a community of organisms among whose members interbreeding readily occurs.
EXTINCTION
the loss of species which decreases the range of organisms on earth, decreasing the biodiversity.
GEOGRAPHIC SPECIATION
when a new species arises from an existing species , when the pops are separated by a geographical barrier
EVIDENCE OF EVOLUTION
- fossil records
- descent w modification
- biogeography
- genetics
DESCENT WITH MODIFICATION
how the basic body plan of organism groups were modified to adapt to their diff environments
BIOGRAPHICAL REGIONS
- large mountain ranges
- deserts
- oceans
WHAT EVIDENCE FOR EVOLUTION DOES GENETICS PROVIDE?
- closely related orgs have more similarities in their DNA
- explains the source of variation that is needed for evolution
- shows how changes in the geno/pheno are transferred through generations
OTHER FORMS OF EVIDENCE
- comparative biochemistry
- vestigial organs
- comparative embryology
NATURAL SELECTION PROCESS
- large number…
- variation
- some have favorable…
- change in environment
- dying out, survival
- reproduce
- higher proportion
- may lead to new species…
PUNCTUATED EQUILIBRIUM EXPLANATION
- these species were in equil until sudden rapid changes interrupted their existence. they either failed to adapt and became extinct, or rapidly experienced many favorable mutations that enabled them to adapt to the new env. these rapid adaptations in order to survive accelerated evol and lead to speciation
GRADUALISM
a slow gradual change in a species
WHAT DOES PUNCTUATED EQUILIBRIUM EXPLAIN
explains how changes leading to speciation may occur very rapidly over short tme and explains the long periods in fossil records where species remain unchanged
