bio exam two Flashcards
what is a species?
a group of organisms that can reproduce with one another in nature and produce fertile offspring
morphological species concept
concept that characterizes a species based on its structural features, different species are morphologically indistinguishable in some cases though separation based on lineage is clear
what do all species concepts share? what is a drawback of this?
share: under all species concepts, a species is a separately evolving metapopulation lineage
drawback: it is exclusively defined in terms of sexual reproduction
What is the result of speciation?
an ancestral species splits into two or more descendant species that are genetically different from one another and can no longer interbreed
In DM model, what happens in each lineage?
a new allele arises and becomes fixed at one point; in the other now diverged lineage, a different allele arises at a different point on the gene
Dobzhansky-Muller Model
predicts that hybrid incompatibility will be due to interactions between at least two genes (one from each species)
allopatric speciation
mode of speciation that occurs when biological populations become geographically isolated from each other and gene flow is prevented/interfered with
what is sympatric speciation?
evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region
what is a ring species?
situation in which two populations which do not interbreed are living in the same region and connected by a geographic ring of populations that can interbreed
What is autopolyploidy?
occurs when organisms have more than two sets of chromosomes from the same species
What is polyploidy?
condition where the cells of an organism have more than one pair of chromosomes
What are the post-zygotic isolating mechanisms? name examples
any factor that reduces/prevents interbreeding between genetically divergent populations or species, but functioning after fertilization has occurred
EX: hybrid inviability, hybrid sterility, and hybrid breakdown
What is allopolyploidy?
when organisms contain two or more sets of chromosomes that are from different species
What are the pre-zygotic isolating mechanisms? name examples
the separation of different species to keep them from creating offspring by preventing the gametes from forming a zygote
EX: spatial isolation, temporal isolation, mechanical isolation, gametic isolation, behavioral isolation
What is a hybrid zone?
areas where genetically distinct populations meet, mate, and leave offspring of mixed ancestry
What is hybridization?
process in which two divergent lineages with independent evolutionary histories come into contact and interbreed to produce offspring with a combination of traits from both parents
How is hybridization selected?
selection based on phenotypic traits of the hybrid
How does hybridization affect fitness?
can reduce fitness by either introducing alleles to a population that are not suited to the local environment or disrupting co-adapted gene complexes
What factors influence whether a lineage will diverge? name factors & examples
-genetic factors
-ecological factors
-geographic factors
-reproductive factors
-selection pressures
-genetic drift
-gene flow
What happens during diet speciation?
populations diverge and eventually become reproductively isolated due to differences in their ecological niches and dietary preferences
name processes that may occur during diet speciation
ecological divergence, trait evolution, reproductive isolation,
gene flow reduction, speciation
What does a pollinator do?
helps carry pollen from the male part of the flower (stamen) to the female part of the same or another flower (stigma)
what is sexual selection?
natural selection arising through preference by one sex for certain characteristics in individuals of the other sex
what is dispersal?
ecological process involving movement of individual(s) away from the population in which they were born to another location, or population, where they will settle and reproduce
How do pollinators affect speciation rates?
enact mating events between plants and, in doing so, conduct gene flow across the landscape
How does sexual selection affect speciation rates?
could accelerate speciation via increased coevolution of male traits and female preferences in allopatric populations or if traits involved in mate recognition were under direct environmental selection
How does dispersal affect speciation rates?
species which disperse over larger geographical distances may have much higher speciation rates
Geologic Time Scale
system used by geologists, paleontologists, and other Earth scientists to organize and categorize Earth’s history into distinct periods based on significant events, changes in life forms, and geological processes
Stratigraphy
branch of geology that deals with the study of rock layers, or strata, and their relationships within the Earth’s crust and involves the analysis, interpretation, and correlation of sedimentary, volcanic, and metamorphic rock layers to reconstruct the geological history of a region
Strata
layers of sedimentary rock that contain fossils and other evidence of past life, formed over time through the accumulation and compaction of sediments, such as sand, mud, and organic matter & usually studied for evolutionary history
Sedimentary Rock
one of the three main types of rock found on Earth’s surface, formed through accumulation, compaction, and cementation of sediments derived from the weathering and erosion of pre-existing rocks, minerals, and organic materials
Radiometric Dating
technique used to determine the age of rocks, fossils, and other geological materials based on the decay rates of radioactive isotopes
Radioisotopes
isotopes of chemical elements that exhibit radioactive decay & essential components of radiometric dating methods because they decay at known rates, allowing scientists to calculate the age of geological samples based on the proportions of parent and daughter isotopes present
Half-life
time it takes for half of the radioactive atoms in a sample to decay into stable daughter atoms, specific to the particular decay process
when was the Hadeon eon?
4.6 billion years ago (Earth’s formation) to about 4 billion years ago
when was the Archean eon?
spans from about 4 billion years ago to 2.5 billion years ago
when was the Proterozoic eon?
spans from 2.5 billion years ago to 541 million years ago