final Flashcards
mammals
amniotes that have hair and produce milk
characters of mammals
-mammary glands-produce milk
-hair
-a larger brain than other vertebrates of equivalent size
-differentiated teeth
early evolution of mammals
from synapsids, two jaw bones were incorporated into inner ear
synapsids
what mammals derived from, tetrapod vertebrates
monotremes
a small group of egg laying mammals consisting of echidnas and platypus
marsupials
animals that continue development in mothers sac, kangaroo, opossum, koala
marsupium
the pouch of a marsupial
placenta
temporary organ that forms to create womb
convergent evolution in marsupials
marsupials in australia resemble eutherians in rest of the world due o convergent evolution
eutherians
a group of mammals with a placenta and reach an advanced state before birth
primates
lemurs, monkeys, apes, tarsiers
derived characters of primates
-hand and feet adapted for grasping
-large brain, short jaw
-forward looking eyes for depth perception
-social behavior and parental care
-opposable thumb
opposable thumb
thumb placed opposite of the fingers used for grasping
living primates
-lemurs, lorises, pottos
-tarsiers
-anthropoids
anthropoids
monkeys and apes
new and old world monkeys
apes
derived from old-world monkeys
biodiversity
-variety of life
-variability among living organisms from all sources(inter-species, intra-species, and ecosystems)
species diversity
the variety of species in an ecosystem or throughout biosphere
genetic diversity
genetic variation within a population and between population
ecological diversity
species richness/abundance within species, calculated through Shannons index
endangered species
in danger of extinction throughout all or much of its range
threatened species
likely to become endangered in foreseeable future
species concepts and their strenghts/weaknesses
BCEEMPR
biological species
group that can only mate/reproduce with each other
-popular yet irrelevant to asexual species
cohesion species
shared cohesive characteristics, like biological but includes asexual
-cohesion is hard to recognize
ecological species
group that occupies distinct adaptive zone
-hard to determine zones, assumes species cannot share same niche
evolutionary species
lineage of ancestor descendant populations
-vague and difficult to observe
morphological species
-group based on morphological features
-may not actually reflect links due to convergent evolution
phylogenetic species
smallest group of diagnostically different from parental descent
-will give rise to too many species than other concepts
recognition species
group of species that can recognize each other for breeding/fertilizing
-determining if a feature is used to recognize potential mates is difficult/impossible in many species
taxonomic richness
number of different taxa present in each site
shannon’s diversity index
H=-{a(lna) + b(lnb)….}
how is genetic diversity measured
most precisely as nucleotide variation
variation in genome sizes
how genetic diversity is measured
variation in chromosome numbers
shorter chromosomes have more diversity, actual number of chromosomes does not affect that
importance of species number as measure of biodiversity
the most common measure of biodiversity
-practical application
-existing information
-surrogacy
-wide application
fossil record (strengths and limitations)
-not perfect or even depending on time periods
-only small fraction of the record has been recovered
-biased towards most abundant species (soft-bodied organisms don’t fossilize)
molecular biology and its utility in documenting biodiversity
-allows us to build phylogenetic trees of relatedness
-paired organisms with very different sequences diverged early than more closely related ones
molecular clocks
genetic changes used to determine when species diverged
geological record
a timescale that partitions earths history into eras
major events in development of biodiversity
-prokaryotes evolving
-photosynthesis and oxygen revolution
impact of microbes on earth’s conditions
microbes recycle and create primary elements used for living systems (oxygen, carbon, nitrogen)
evolution of eukaryotes and multicellularity
1.5 billion years ago were first ancestors of multicellular eukaryotes
Cambrian explosion and significance to biodiversity
rapid burst of evolution due to increased oxygen levels and shallow ocean waters
evolution of metazoan Hox genes
hox genes introduced to animals allowed for morphological diversity
temporal dynamics in numbers of families of organisms
number of families increased with time
patterns in the dynamics of evolution and extinction of families of organisms
high spikes of extinction
mass extinction and proposed causes for past mass extinctions
abrupt change in climate conditions
estimates of current numbers of species
from 3mil to 100 mil or more
geographic patterns of biodiversity
-not distributed evenly across planet
-applies to terrestrial and aquatic env
-can identify large-scale trend but is significant spacial variation along latitudinal gradients
species-area relationships
with all outside factors being equal, a larger geographical area will have more species
explanations of species-area relationships
colonization/extinction dynamics
-speciation/extinction dynamics
-habitat diversity
island biogeography and colonization/extinction dynamics
-larger geographical areas so immigration is less important for a source of new species
-more area/larger ranges/isolation = greater chance of new species evolving
-population sizes likely larger=reducing extinction probability
local and regional richness relationships
biological realms
a continuous uninterrupted geographical region - rain forest, tropical seas, global coastal zone etc.
contrasts in diversity between oceans and terrestrial realms
-life began in sea
-continental are more heterogenous than marine
-ocean-bed is less elaborate than terrestrial
-herbivory differ between sea and land
-differences in body size distribution of marine and terrestrial
biomes
based on temperature and rainfall, similar biomes can be seen in different realms
hotspot of biodiversity
skewed by countries, some have most species, other have limited biodiversity
endemism
a taxon found in an area and nowhere else
factors increasing levels of endemism
area, latitude, species richness
gradients in biodiversity
latitude, altitude and depth
latitudinal patterns
species richness generally declines along equatorial-polar gradient, is greater in tropics
features of latitudinal gradients
-persistent feature of much of the history of life on earth
-peak of diversity has inflection point north 20-30 degrees
-often asymmetrical about the equator
-steepness of gradient varies with taxon
proposed mechanisms for latitudinal gradients
-area effects
-energy availability
-time
patterns of biodiversity with respect to altitude and depth
