Exam 3 Flashcards
Biological Species Concept
all members have the potential to interbreed under natural conditions and produce viable, fertile offspring.
some hybridization is okay, as long as it doesn’t occur naturally enough to overwhelm the boundary
Morphological species concept
Classifies organisms based on observable phenotypic traits
Phylogenetic species concept
species as an irreducible group whose members are descended from a common ancestor and who all possess a combination of certain defining, or derived, traits
Ecological Species Concept
a species is a set of organisms adapted to a particular niche
Prezygotic barriers
prevent formation of a zygote or fertilized egg
Prezygotic barrier: Habitat Isolation
may occupy the same range and be potentially able to hybridize, but prefer different habitats so never (or rarely) mate
Prezygotic barrier: Temporal Isolation
may potentially interbreed, but are ready at different times
Prezygotic barrier: Behavioral Isolation
species may encounter each other but do not mate because of differences in courtship behavior or other behaviors
Prezygotic barrier: Mechanical Isolation
lock and key…physical barriers that prevent mating (such as genitalia)
Prezygotic barrier: Gametic Isolation
gametes do not recognize each other due to different receptors
Postzygotic barriers
prevent development of viable or fertile offspring
Reduced Hybrid Viability
hybrid offspring don’t develop or don’t survive as well
Example of hybrid infertility
tigon, mules
Hybrid breakdown
1st generation hybrids are fertile, but when they mate the second generation hybrids are sterile or weak
Allopatric Speciation
geographic barrier –> reproductive isolation –> speciation
when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow
Sympatric Speciation
gene flow is restricted from something other than a geographic barrier, resulting in reproductive isolation
Macroevolution
evolution of groups larger than an individual species
Gradualism (Anagenesis)
species continue to exist and survive as an interbreeding population…no branching or splitting into separate species (gradual, slow, constant change)
Punctuated Equilibrium (Cladogenesis)
the formation of a new group of organisms or higher taxon by evolutionary divergence from an ancestral form
emphasizes periods of stasis interspersed with periods of rapid change
Stasis
long periods of subtle evolutionary change
Causes of Stasis
stabilizing selection keeping the species from changing; variable directional selection that keeps the species fluctuating around a mean; genetic/developmental constraints
Mosaic Evolution
in monotremes: the evolutionary change of different adaptive components of the phenotype of an organism at different times or at different rates in an evolutionary sequence
Rapid change
origin of new species and characteristics of a time period that is short relative to the period of stasis
does not say that speciation is instantaneous, just too quick to capture in fossil record
Causes of rapid change
environmental change (cambrain explosion); ecological opportunity
6 origins of evolutionary novelty
Exaptation, duplication, serial homology, heterchrony, lateral gene transfer, homeotic genes and pattern formation
Exaptation
evolution is a tinkerer…a shift in the function of a trait during evolution
flowers are modified leaves
Duplication
evolution of genes with novel functions: duplicated genes can evolve different novel functions
Serial Homology
When two or more organs or structures are basically similar to each other in construction but are modified to perform different functions
arthropod limbs
Heterochrony
changes in developmental timing can radically alter the adult appearance of an organism
Lateral Gene Transfer
horizontal movement of individual genes, organelles or fragments of genomes from one lineage to another
happens a lot with bacteria
Homeotic genes and pattern formation
simple developmental/genetic changes can have major effects
flowers/arthropod appendages
3 types of Prokaryotes
Archaea, Eukarya, Bacteria
Prokaryotes
a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles
-no nuclear envelope around genetic material
-no membrane bound organelles (only have ribosomes)
-circular DNA, with relatively few genes in plasmids
-no mitosis/meioisis…binary fission!
Parts of Prokaryote Genome
Chromosome
Plasmids…facilitate lateral gene transfer
Mechanisms of Lateral/Horizontal Gene Transfer
Transduction: genes via virus infection
Conjugation: plasmids from live bacteria
Transformation: genes from environment, such as dead bacteria/archaea
Photoautotroph
energy from light, carbon from CO2
plants
Chemoautotrophs
energy from inorganic, carbon from CO2
some prokaryotes
Photoheterotrophs
energy from light, carbon from organic compounds
some prokaryotes…non sulfur bacteria
Chemoheterotrophs
energy and carbon from organic compounds
humans
Aerobic Respiration
sugar + O2 –> ATP + CO2
Endosymbiosis Theory
Eukaryotes arose from prokaryotes living inside each other
What are the evidences of Endosymbiosis?
-Similar types of endosymbiosis: protists inside each other and protists inside animals
-Size: mitochondria and chloroplasts are similar in size to prokaryotes
-Similar membranes: membranes of prokaryotes and memberanes of mitochondria/chloroplasts have similar properties (enzymes, transport system)
-Mode of replication: mitochondria/chloroplast reproduction is similar to binary fission
-Mitochondrial and chloroplast genome resembles prokaryote genome: simple genome with circular DNA
-Mitochondria and chloroplast transcription: have their own ribosomes and coding seqeunces similar to bacteria
Secondary Endosymbiosis
A heterotrophic protist engulfed an algal containing plastids (eukaryote taking in another eukaryote)
Binary Fission
asexual reproduction by a separation of the body into two new bodies. An organism duplicates its DNA, and then divides into two parts (cytokinesis), with each new organism receiving one copy of DNA
Mitochondria evolved from
proteobacteria
Chloroplasts evolved from
cyanobacteria
Eukaryote
an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus
Analogous trait
similarities (same function) that are independently evolved
Homologous trait
shared derived trait
Monophyletic
single origin…an ancestral species and all the descendant species grouped together
Polyphyletic
convergent similarity
Paraphyletic
single origin: ancestral species but includes only some of the decendents
Synamorphy
shared derived trait
Parsimony
the cladogram requiring the fewest evolutionary changes is usually preferred
Closest relative of modern plants
green algae
closest relative to land plants
charophyceans
Peripatric Speciation
a small group breaks off from the larger group and forms a species as a result of physical barriers
Parapatric Speciation
a species is spread out over a large area, so mating is restricted to a smaller vicinity
Advantages of plants moving to land
-More sun
-more carbon dioxide
-more nutrients
Disadvantages of plants moving to land
-Waterloss/drying out
-reproduction
Land plant adaptations
-cuticle…waxy covering to prevent water loss
-vascular tissue…tubes that transport materials up and down the plant, containing xylem to move water and phloem to move sugars
-seeds…instead of spores, allow plants to reproduce without needing water and provide protection/food in a dry environment
-fruits/flowers…more effective reproduction through pollination, less inbreeding, more efficient seed dispersal
Sporophyte
produces spores by meiosis (asexual)
Gametophyte
produces gametes by mitosis (sexual)
Reproduction of plants
alternation of generations between sporophyte and gametophyte
examples of nonvascular plants
mosses, liverworts, hornworts
Types of vascular plants
Ferns, Gymnosperms, Angiosperms
-seedless vascular plants
-leaves arose
-fragile gametophyte stage
-relies on water for reproduction
-sporophyte is the dominant generation in life cycle
Ferns
-no ovaries
-evolution fo seeds
-reduction of the gametophyte
-primarily relies on wind pollination
Gymnosperms
-large sporophytes and tiny gametophytes
-flowers
-seeds
-fruits
Angiosperms
Metazoans
Animals
Eumetazoa
true tissue animals
gastrulation, nervous system, synapses, radial symmetry
Porifera
Sponges
no true tissues, no symmetry, hermaphrodites, asexual, adults sessile, larvae motile, spicules, filter feeders
Cnidarians
Jellyfish, sea anemone, coral
radial symmetry, diploblastic, polyp and medusa, eumetazoa (but only two tissue layers), aseuxal (budding) and sexual, gastrulation, nematocysts (stinging organelles)
Diploblastic
ectoderm and endoderm but no mesoderm
Gastrulation
creates ectoderm, endoderm, and mesoderm
embryo transforms from a one-dimensional layer of epithelial cells, a blastula, and reorganizes into a multilayered and multidimensional structure called the gastrula
Zygote —> cleavage (mitosis) —> blastula —> gastrula
Cambrian Explosion
Around 530 million years ago, a wide variety of animals burst onto the evolutionary scene…huge increase in diversity as a result of rising oxygen levels and oceanic calcium concentrations
Bilaterians
-bilateral symmetry
-cephalization
-anterior and posterior
-directional movement
-triploblasty
Cephalization
development of head and sense organs in the front
Triploblasty
ectoderm, endoderm, and mesoderm
forms muscle and supports organs
Coelomates
animals with body cavity that develops within the mesoderm
more control over movements of fluids in body cavity, better support of organs, better digestion
Protostomes
blastopore becomes the mouth
Types of Protostomes
Lopotrochozoa and Ecdysozoa
Lophotrochozoa
lophophore feeding structure
flatworms, segmented worms/annelids, mollusca
Segmentation
convergent evolution (annelids, arthropods, and cordates)
can operate segments independently…facilitates specialization of different body regions
Mollusca
-radula…feeding organ
-muscular foot, mantle, visceral mass
open circulatory system
Ecydysozoa
Roundworms, Arthropods
Roundworms
nematoda
pseudocoelomate
often parasitic
decomposers in soil
Arthropods
-jointed appendages
-regional segmentation
-exoskeleton
-open circulatory system
-trilobites, chelicerates, millipedes and centipedes, crustaceans, insects
Deuterostomes
blastopore becomces anus
Types of Deuterostromes
Echinoderms and Cordates
Echinoderms
Starfish
body symmetry differs in adult and larval (larvae bilateral)
pentaradial symmetry
water vascular system with tube feet
Cordate Characteristics
-Notocord
-Pharyngeal gill slits
-Dorsal hollow nerve cord
-Muscular, post-anal tail
Derived Traits of Primates
-large brain, short jaw
-forward-looking eyes close together
complex social behavior/parental care
fully opposable thumb
DNA methods
-sequence the same stretch of DNA in different species
-determine differences in nucleotide sequences between species
How much neanderthal DNA do we have
1-4%…only if ancestry outside of Africa
Bipedalism
ability to walk on two feet
Out of Africa (Monogenesis or replacement hypothesis)
Suggests recent common ancestor of Homo sapiens probably in Africa…modern humans dispersed from Africa displacing other hominins
What are humans
anthropoid primates, homo sapiens
Invertebrate Chordates
Tunicates (sea squirts): sessile adults
Lancelets: notochord persists throughout life, live in shallow marine and brackish water, filter prey from water with pharyngeal basket
Vertebrate characteristics
-jointed skeleton
-extreme cephalization
-great sense organs
-closed circulatory system
-internal organs suspended in coelom
Craniates
neural crest cells
more active than lancelets and tunicates
jawless fish (hagfish, lamprey)
Jawless vertebrates
Jawless fish, Agnathans (hagfish, lamprey)
Gnathostomata
jawed vertebrate
Chondrichthyes
Sharks and rays
cartilaginous fish
Osteichthyes
Bony fish
-ossified skeleton
-gills covered by operculum
-swim bladder
-ray finned fish
-lobe finned fish
-lungfish
Tetrapoda
Amphibians, Reptiles, Birds, and Mammals
-jointed appendages
Amphibians
salamanders, frogs, caecilians
eggs lack shell and must stay moist
Amniotes
reptiles, birds, and mammals
Amniotic egg
-protection of embryo from environment
-storage of wastes
-gas exchange
-yolk sac
Archosaurs
birds and crocodilians
High metabolic rate in archosaurs and mammals
(convergent)
-high body temp
-efficient locomotion
-efficient respiration
-homeothermic
-four chamber heart
Birds
flight with feathers and wings
honeycombed bones
complex courtship
Mammals
-platypus and echidna lay eggs
-hair
-lactation
-three-bone middle ear
-sweat glands
3 Groups of Mammals
Monotremes…egg laying
Marsupials…pouches
Eutherian…placental
Adaptive Radiation
new niches open up (due to the removal of old organisms or new areas opening up)
