Biology 100 Unit 14 Flashcards
is the study of major biological changes seen in the fossil record (i.e., obvious structural differences).
macroevolution
When changes accumulate to produce a completely distinct group of organisms, we call this ___________.
speciation
-This includes the origin of a new species (speciation).
According to the ______________________, a species is a group of members in a population with the potential to interbreed and produce fertile offspring.
Biological Species concept
According to the biological species concept a species is a
group of members in a population with the potential to interbreed and produce fertile offspring.
Members of different species don’t mate due to
reproductive isolation.
The biological species concept can be problematic. – Some pairs of clearly distinct species occasionally
interbreed and produce _____________.
hybrids
– For example, grizzly bears and polar bears may interbreed and produce hybrids called ____________.
groolarbears
_________________may bring these two bear species together more frequently and produce more hybrids in the wild.
– These 2 distinct species would not be reproductively isolated from each other, therefore difficult to classify as _______________________
– Alternate species concepts can be useful.
Melting sea ice
distinct species.
Another species definition is the __________________ ____________, which identifies species in terms of their ecological niche, looking at their role in an community.
ecological species definition
The ecological species concept
focuses on unique adaptations to particular roles in a
biological community.
or example, two species may be similar in appearance but distinguishable based on
- what they eat
- where they live
Lastly, the ___________________defines a species as the smallest group of individuals that share a common ancestor, forming a branch on an evolutionary tree.
phylogenetic species concept
Biologists trace the phylogenetic history of a species by comparing its
DNA sequences
Alternate ways of defining species using physical traits, shape, size or other features.
Morphological species concept
Give two examples of the morphological species concept
- asexual organisms
- fossils
prevent interbreeding and establish different species.
reproductive barriers
What do reproductive barriers do
the isolate gene pool
barriers prevent mating between different species.
prezgotic or postzygotic
Generally fertile offspring are the result
of the same species mating, with few exceptions.
Courtship ritual in blue-footed boobies is an example of one kind of prezygotic barrier, ________________.
behavioral isolation
Structural differences don’t allow the genitals of these snails to mate
mechanical isolation
mating or fertilizing occurs at different seasons
temporary isolation
populations live in different habitats and therefore do not interact
habitat isolation
Female and Male gametes fail to unite in fertilization
gametic isolation
Should prezygotic barriers fail and interspecific fertilization occur forming a hybrid zygote, postzygotic barriers are additional mechanisms which
prevent future hybrids from developing
Post zygotic barriers: most hybrid offspring do not survive.
reduced hybrid viability
hybrid offspring are vigorous but sterile.
Reduced hybrid fertility
the first-generation hybrids are viable and fertile but the offspring of the hybrids are usually sterile.
hybrid breakdown
There are two main modes of speciation:
- allopatric speciation
- sympatric speciation
Geographic isolation may cause a population to become genetically unique as its gene pool is changed by natural selection, genetic drift, or mutation.
allopatric speciation
Sympatric speciation occurs if a _________________ _______________________ between parents and offspring
mutations may result in plant with a different number of chromosomes
This is _________________: a multiple number of chromosomes,
poly ploidy
If a parent cell fails to divide after DNA replication occurs, chromosomes duplicate, then ______________________ ______________________________________________.
self fertilize may result in plant with a different number of chromosomes
This plant may be incompatible with others (due to the newly increased chromosome number) and considered a
distinct species.
A farmer sows grain kernels from mixed plants in the wild.
Some of the plants in the field hybridize and self-fertilize.
As a result, many domesticated plants are the result of sympatric speciation
The evolution of many diverse species from a common ancestor is ______________________.
adaptive radiation
An example of adaptive radiation can be found on the Galápagos islands
with the 14 different finch varieties considered to have arisen from a common ancestor from the mainland.
n speciation,
a gradual accumulation of many changes, may account for a new species.
speciation is called ________________, explaining how a new species evolved through the gradual accumulation of changes brought about by natural selection.
gradualism
However, __________________________are found in the fossil record.
few transition fossils are found
The _______________________ model is a contrasting model of macroevolution.
punctuated equalibrium
This model proposes that species diverge in _______ ____________________ as a population diverges from the ancestral populations, with little or no change occurring for the remainder of the species’ existence.
spurts of relatively rapid change
This would account for the relative _______________ ___________________________.
rarity of transitional fossils
___________________: long periods of little change, or equilibrium punctuated by abrupt episodes of speciation
punctual equalibrium model
__________________: Slow gradual changes over time
gradualist model
But, how long exactly is a “punctuation”?
A punctuation may involve hundreds of generations.
_______________________________changes may have occurred during the existence of a species.
both gradual and punctual
This means that, in evolutionary time, even a ____________________change may take longer than humans can directly observe.
“punctuated”
