Introduction Lectures (pre-phyla)

what are the eight characteristics of living things

chemical uniqueness, complexity and hierarchical organization, reproduction, possession of genetic program, metabolism, development, environmental interaction, movement

what does chemical uniqueness mean

organism has complex molecular organization of macromolecules

what is the hierarchical organization

atoms, molecules, macromolecules, cells, tissues, organs, systems, organisms, populations, species

what does possession of a genetic program mean

the central dogma (DNA, RNA, protein) and genetic code

what are the two types of synthesis of macromolecules

autotrophs and heterotrophs

what does having development mean

characteristic life cycle and a change from initial form to final adult form

what does it mean to have movement

living organisms initiate controlled movements and use energy extracted from environment

what is the oparin-haldane hypothesis

primordial soup theory - organic compounds formed slowly over time from simple molecules to more complex organisms. Tested by Miller and Urey

what is the miller-urey experiment (1953)

they circulated a mixture of water, hydrogen, methane, and ammonia. they used an electrical spark as an energy source

Results: carbon in the mixture was converted into organic compounds

what is the formation of polymer stage in the origins of life

within semipermeable amphiphilic membranes

in aq. solution, polymers would tend to be hydrolysed and the semipermeable membranes could provide protection

what is chemical evolution

formation of complex organic molecules from simpler inorganic molecules through chemical reactions

first step in development of life

what is organic evolution

process by which changes in the genetic composition of populations of organisms occur in response to environmental changes (descent with modification)

what are the foundations of Darwin and Wallace’s theory of natural selection

geology: showed that the physical planet was not static

economics: information about population pressure (the idea of supply and demand)

embryology: homologies among different organisms and how that indicates commonality

what are the five theories that summarize Darwinian Evolutionary Theory

perpetual change, common descent, multiplication of species, gradualism, natural selection

which of the five theories are universally accepted and which are tentatively accepted

perpetual change, common descent, multiplication of species are universally accepted

gradualism and natural selection still have unresolved aspects

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what is the theory of perpetual change

the living world is always changing, evidenced in the fossil record

how is the fossil record biased

hard structures are better preserved than soft animals so there are gaps in out knowledge based solely off fossil record

what is the theory of common descent

all organisms are descended from LUCA as evidenced by organismal form, cellular structure, universality of genetic code

evidence for common descent

the same as the eight criteria for life

homology

similarity of parts or organs of different organisms caused by evolutionary derivation from a corresponding part or organ in a common ancestor

homologous features are transmitted to all descendant lineages

what is the theory of multiplication of species

evolution produces new species by splitting and transforming older ones

what is the theory of gradualism

small changes accumulate steadily over time

what is the evidence AGAINST gradualism

it is not always supported by the fossil record

changes have capacity for be substantial and sudden

what is punctuated equilibrium

long periods of stasis/equilibrium, punctuated by brief events of speciation (proposed in response to lack of evidence for gradualism)

stasis

periods of equilibrium where a species doesn’t change significantly or at all

what is the theory of natural selection

the process where organisms better adapted to their environment tend to survive and reproduce more

explains adaptation

adaptation

a change or the process of change by which an organism or species become better suited to its environment

requirements for natural selection

variation in traits, differential reproduction, heredity

then more advantageous traits become more common in a population

how do complex traits evolve

advantageous intermediates, exaptation

what are advantageous intermediates

the intermediate step during evolution might be advantageous in itself

(early wing made running faster)

what is exaptation

process by which features acquire functions for which they were not originally adapted or selected

structure is evolved for one purpose, but then evolves further to serve another purpose

what is microevolution

evolutionary changes in frequencies of variant forms of genes within populations

what is macroevolution

evolution on a long timescale

includes origin of new species, structures, mass extinctions, etc.

what are the patterns in macroevolution

stasis, lineage splitting, extinction

what are the types of speciation

allopatric and sympatric

what is allopatric speciation

an ancestral population is geographically divided and the isolated subpopulations evolve reproductive barriers between them

what are the two types of allopatric speciation

vicariant speciation and founder effect

what is vicariant speciation

climate or geology causes populations to fragment. the fragments of the ancestral population are left intact

ex. isthmus of panama and the snapping shrimp

what is the founder effect

when a small number of individuals disperse to distant place and form new populations

causes a reduction in population size and a subsequent loss in genetic variation

what is sympatric speciation

diverging lineages co-occupy a geographic area

different individuals within a species begin to occupy different components of the environment

ex. apple maggot fly and blueberry maggot fly

biological species concept

characterizes species by their ability to interbreed to produce fertile offspring

morphological species concept

characterizes species by body shape and other features

ecological species concept

characterizes species in terms of its ecological niche

interspecific hybrid

offspring produced by mating of individuals from two different species

can sometimes be fertile and mate with another or either of their parental species

general agreement on species by biologists

individueals descend from a common ancestral population

reproductive compatibility

genotypic and phenotypic cohesion

phylogeny

the origin and diversification of any taxon, or the evolutionary history of its origin and diversification

phylogenetic tree

tree diagram whose branches represent current or past evolutionary lineages and which shows the hypothesized patterns of common descent among those lineages

homology vs homoplasy

homology: character similarity resulting from common ancestry

homoplasy: non-homologous similarities that may be found in various organisms (not inherited from a common ancestor)

ex. bird and bat wings are homoplasy BUT bird and bat forelimbs are homologous

cladistics

an approach or methodology for classifying organisms based on common evolutionary descent

accomplished by comparing morphological, chromosomal or molecular characteristics and sometimes even behavioural and ecological features are used

what is the goal of cladistics

to infer the evolutionary tree that relates all extant and extinct species

cladogram

a diagram used in cladistics to show evolutionary relationships between organisms

clade

a unit of evolutionary common descent that includes ancestral lineage and all descendants

ancestral character

character state present in the common ancestor

derived character

all other variant forms of the character that arose later within the group

monophyletic clade

includes the most recent common ancestor and all descendants of that ancestor

paraphyletic clade

includes the most recent common ancestor and some BUT NOT ALL of that ancestor

polyphyletic clade

does not include the most recent common ancestor of all members of a group (the group has at least two separate evolutionary origins

sexual reproduction

fusion of two specialized cells/gametes

asexual reproduction

no special reproductive organs or cells, involves only one parent, produces genetically identical offspring

advantages of asexual reproduction

quick and energy efficient

sexual reproduction takes about twice as long as asexual reproduction (in species that do both)

disadvantages of asexual reproduction

phenotypic diversity relies on mutation

deleterious mutations accumulate

advantages of sexual reproduction

ability to mix and match successful genes

more rare and novel genotypes

disadvantages of sexual reproduction

energetically costly

males do not directly produce offspring

it takes two individuals to make one offspring

binary fission (asexual)

the parent divides by mitosis into two parts and each part grows into an individual that is similar to the parent

multiple fission or schizogony

nucleus divides repeatedly

then cytoplasmic division produces many daughter cells

budding (asexual)

unequal division of an organism (bud is an outgrowth that develops organs and detaches from parent)

gemmulation (asexual)

formation of a new individual from an aggregation of cells that are surrounded by a resistant capsule (a gemmule)

fragmentation (asexual)

organisms breaks into two or more fragments that both become a new individual (each fragment grows new parts)

bisexual reproduction (sexual)

two haploid (one male and one female) gametes combine to form a zygote

hermaphroditism (sexual)

male and female organs occur in the same individual, but most avoid self-fertilization

pathernogensis (sexual, but sometimes asexual)

embryo develops from unfertilized egg

sperm may activate but not fuse with egg

dioecious

having male and female gonads in separate individuals

monoecious

having both male and female gonads in the same organism

oviparous

reproduction in which eggs are released by the female

development of offspring occurs outside the maternal body

external or internal fertilization

viviparous

reproduction in which eggs develop within the female body, which provides nutritional aid

internal fertilization

ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent

hatch within the parent or immediately after laying

internal fertilization

derive nourishment from yolk, not from mother

what is the order of gamete development

gamete formation, fertilization, cleavage, gastrulation, organogenesis, growth

what is an egg/ovum

an organic vessel where an embryo develops/the female reproductive or germ cell

what does an egg contain

normal somatic cell components, yolk

they have a polarity (animal pole and vegetal pole)

what is the animal pole of an egg

most of the cytoplasm and the nucleus

what is the vegetal pole of the yolk

most of the egg

isolecithal yolk placement

very little yolk, evenly distributed through egg

typical of placental mammals

mesolecithal yolk placement

moderate amount of yolk concentrated at vegetal pole

typical of amphibians

telolecithal yolk placement

abundance of yolk densely concentrated at vegetal pole

typical of birds, reptiles, and fish

centrolecithal yolk placement

large centrally located mass of yolk

typical of arthropods

amount of yolk - developmental patterns

lots of yolk usually means young exhibit direct development

little yolk usually means young go through larva stage/indirect development

cleavage

embryo divides repeatedly without growth (skips G phase)

single large egg cell becomes smaller blastomeres

by end of cleavage, zygote is called a blastula

what are the two types of cleavage

holoblastic and meroblastic

holoblastic cleavage

complete and approximately equal divisions of cells

meroblastic cleavage

cleavage restricted to a small area of egg

what are the directions of cleavage

spiral or radial

blastocoel

fluid-filled cavity that animals are formed around

gastrulation

conversion of the spherical blastula into a two or three layered embryo

the layers are called germ layers

invagination

one side of the blastula bends inward

then an internal pouch is formed to make the gut cavity (aka archenteron or gastrocoel)

blastopore

the opening to the gut cavity

ectoderm

outer layer of cells (lining blastocoel)

endoderm

inner layer of cells (lining gut)

blind gut

when the gut only opens at the blastopore

difference between protostomes and deuterostomes

blastopore in protostome develops into a mouth

blastopore in deuterostome develops into an anus

mesoderm

third layer that is formed from the endoderm