species and speciation Flashcards
what is a nested hierarchy of life?
made by carl linnaeus
its a way to identify how species relate to each other
categorized based on similar traits
starts broad and get more specific
what is a species?
group of organisms that are biologically distinct from other and evolving along lineages
what is a species concept?
a set of conditions that are necessary and sufficient to identify a group of individuals as a species
don’t only define what a species is but also define what speciation is
what is morphological species concept?
all individuals of a species share measurable traits that distinguish them from individuals of other species
based on notable differences in phenotype
what are the pros for morphological species concept?
a practical approach that everyone understands
focuses on novelties that have arisen over time
used for classifying fossil records
not focusing on selection and evolution
what are the cons of morphological species concept?
not useful where species exhibit substantial phenotypic polymorphism or belong to rings
not useful when there is lots of superficial phenotypic differences between putative species/groups
what is biological species concept?
based in the ability of populations to interbreed and produce viable offspring
under natural conditions
what are the pros for biological speciation?
many sister species are hard to distinguish
uses own perceptions to set limits
key unit of evolutionary change and that gene flow is the glue that holds species together
studies reasons that underlie reproductive isolation
what are the cons for biological species concept?
can only be used for living populations, no temporal dimensions relies on sexual reproduction
populations/species near each other can mate
doesn’t apply to organisms created by hybridization
what are pre zygotic isolating mechanisms?
temporal, ecological, behavioural, mechanical and gamete mortality
acts prior to the production of a zygote (fertilized egg)
what are post zygotic isolating mechanisms?
hybrid inviability and hybrid sterility
acts after the zygote formation
what are subspecies?
a taxonomic subdivision of a species
what is a species ring?
a species with a geographic distribution that forms a ring around uninhabitable terrain
what is a cline?
a pattern of smooth variation in a characteristic along a geographic gradient
what is sexual reproduction?
gametes from mother and father are passed to offspring
what is parthenogenesis?
only passes genes to daughter and nothing else, no male needed
what is hybridogenesis?
passes on what gamete they got from their mom and pairs it with a male gamete
same mother gamete is passed on
what is gynogenesis?
copying entire genome and passing it on to offspring, no male gamete in offspring’s genome
male gamete only triggers the copying of the genome
what is a reproductive isolating mechanism?
biological characteristic that prevents the gene pool of 2 species from mixing
what is a hybrid?
an organism produced by mating between parents of different species or sub species
what is ecological isolation?
prezygotic isolating mechanism
species live in same geographical region occupy different habitats
what is temporal isolation
pre zygotic isolating mechanism
live in same habitat but breed at different times of day or different times of year
what is biological isolation?
prezygotic isolating mechanism
nonliving tissues between the vascular cambium and the stem surface
signals of one species isn’t recognized by the other
what is mechanical isolation?
prezygotic isolation
differences in the structure of reproductive organs or other body parts
what is gametic isolation?
prezygotic isolation
incompatibility between the sperm of one species and the eggs of another; may prevent fertilization
what is hybrid inviability?
postzygotic isolating mechanism
hybrid individual has low probability of survival to reproductive age
what is hybrid sterility?
postzygotic isolating mechanism
hybrid offspring cannot form functional gametes
what is hybrid breakdown?
postzygotic isolating mechanism
hybrids are capable of reproducing but their offspring have either reduced fertility or reduced viability
what is ecological species concept?
groups of individual organisms adapt to particular resources (niche) in the environment
delineations based on niche usage
emphasis on selection, wedge between different groups
what are the pros of ecological species concept?
uses species own ecological usage to set limits
strong biological and evolutionary change
emphasis on selection as important force preventing intermediate forms
what are the cons of ecological species concept?
many sister species use same resources
defining niche use can be very difficult
many species are flexible in niche
can’t use on extinct populations
what is the phylogenetic species concept?
species are a diagnosable cluster of individuals within which there is a parental pattern of ancestor and decent
based on common ancestry
look at genome of species
see if there is genetic similarities
what are the pros of phylogenetic species concept?
considers temporal nature if species
no complicated sub species designations
not troubled by possibility that slightly different geographic forms might interbreed
what are the cons of phylogenetic species concepts?
too easy to meet species threshold
- results in more rare species
divisions based on minor differences
uni parental species, little gene flow
groups that reproduce may not remain separate species due to gene flow
what is the practical species concept?
species delineations based on subjective judgement of any competent systematist
what are the pros of practical species concept?
decisions based in careful consideration of all available info, flexible criteria for different taxa
what are the cons for practical species concept?
no philosophically satisfying what happens when 2 competent systematists disagree
what is differential fitness species concept?
species are groups of individuals that are reciprocally characterized by features that would have negative effects in other groups. can’t regularly exchange between groups upon contact
differences may be due to differential adaptation, genetic drift, or other non adaptive processes
what are the pros to differential fitness species concept?
allows exchange of genes
recognizes species specific features arise via reproductive isolation and differential selection
reproductive isolation is not necessary (doesn’t require restricted reproduction)
applicable to uni-parental and bi parental organisms
what are the cons of differential fitness species concepts?
can only be used easily in living populations
need to know the fitness effect of trait variation (hard to figure out)
how to deal with lineages of individuals inhabiting the same environment but carrying different selectively natural alleles
what is retrospective reproductive community concept?
species delineations are only calid looking back in time
what is the problem with species concepts?
each species concept tells us part of the story of biodiversity
trade off between concepts that are universal vs. those that are specific
what is allopatric speciation?
the evolutions of reproductive isolating mechanisms between 2 populations that are geographically separated
different countries or separated by a physical barrier
no genetic flow
what is a species cluster?
a group of closely related species recently descended from a common ancestor
separated and changed on their own
what is secondary contact?
contact after a period of geographical isolation
what is species fusion?
merger of 2 populations into one after the establishment of secondary contact
what are hybrid zones?
a geographical area where hybrid offspring of 2 divergent populations or species are common
what is reinforcement?
- enhancement of reproductive isolation that had developed while populations were geographically separated
- encouraging or establishing a pattern of behaviour using a positive or negative stimulus
what is sexual reproduction?
can lead to speciation
strong mating within own population
what is parapatric speciation?
same geographical area in adjacent countries
mutations occur over time
selective barriers (phenotypic traits for specific environment)
somewhat controversial
what is sympatric speciation?
speciation that occurs without the geographic isolation of populations
rare
no barriers
most controversial
what is a host race?
population that may be reproductively isolated from other populations of the same species as a consequence of their adaptation to feed on specific host plants
what is polyploidy?
the condition of having one or more extra copies of the entire haploid complement of chromosomes
what is autopolyploidy?
genetic condition of having more than two sets of chromosomes from the same parent species
what is unreduced gametes?
a gamete that contains the same number of chromosomes as a somatic cell
what is allopolyploidy?
genetic conditions of having 2 or more complete sets of chromosomes from different parent species
what are the chromosomal alterations?
deletion, duplication, translocation, and inversion
what is deletion?
broken segments lost from chromosome
what is duplication?
broken segments inserted into homologous chromosome
what is inversion?
broken segments reattached in reversed orientation
what is translocation?
broken segments attached to nonhomologous chromosome
what is inversion a problem?
they can’t recombine during meiosis due to chromosomes not lining up in the same orientation
what is genetics mechanisms of speciation?
gradual and or accumulation of genetic differences over time
involve few or many traits
what is nondisjunction?
failure of homologous pair separation during meiosis 1
failure of chromatid separation during meiosis 2
what are the changes in chromosomal numbers?
euploids, aneuploids and polyploids
what are euploids?
normal number of chromosomes
what are aneuploids?
extra or missing chromosomes
what are polyploids?
extra sets of chromosomes
spindle fails during mitosis
