Biology Diversity of Life Exam 3

Phylum Chordata key characteristics

notochord, dorsal hollow nerve cord, pharyngeal gill slits, endostyle, post-and-tail

Subphylum Urochordata

tunicates or sea squirts

subphylum cephalochordate

lancelets

subphylum vertebrata

the nerve cord is surrounded by a series of hard vertebrae made of either cartilage or bone

Infraphylum Hyperotreti

retain notochord through adult stage; lack jaws, mouth with 4 paired fins; possess slime glands and are excessively slimy

Class Petromyzodontida: Lampreys

ancerstors are ostracoderms, first known vertebrates, lack jaws, notochord in juveniles only, no paired fins, have skeleton of cartilage

class Chondrichthyes: cartilaginous fishes

ancestors are placoderms, first known jawed vertebrates; Chondrichthyes appear around 370, key innovation: jaws; paired fins, have 2 chambered heart, have skeleton of cartilage, skin covered by placoid scales

class Osteichthyes: bony fishes

ancestors are placoderms, first known jawed vertebrates, largest group of vertebrates; key innovation: Skeleton made of bone; possess jaws, paired fins, have 2 chambered heart, skin covered by dermal scales, 2 groups: ray-finned fishes and lobe-finned fishes

Class Amphibia

ancestors are lobe-finned fishes; primarily terrestrial as adults and aquatic as juveniles, key innovation: possess 4 limbs, have 3 chambered heart, skin lacks covering; may be used for breathing, lack an amniotic egg

Class repitilia

first appear around 315 my ago, primarily terrestrial but some aquatic, key innovation: amniotic egg; have 3 or 4 chambered heart, skin covered by scales

anapsids

have no openings or fenestra behind the eye socket

synapsids

have a single fenestra

diapsids

have two fenestrae

class reptile: birds

formerly class aves, first appear 150 my ago, closely related to one group of dinosaurs, key innovation: body covered with feathers, endothermic, amniotic eggs, possess wings

bird ancestry

archaeopteryx lithographica

avian characteristics of birds

feathers, endothermic, claws on feet, hollow bones, oviparous, sexual dimorphism

Why are birds in class reptilia?

heterogametic females, feathers are modified scales, primitive birds had teeth, scales on feet and legs, lay eggs, claws not nails, nictitating membranes

class mammalia

first appear around 160-200 my ago, evolved from a group of early reptiles, key innovations: hair, mammary glands for feeding young, endothermic

monotremes

egg-laying mammals

marsupials

pouched mammals

placental mammals examples

cows, mole rats, capybara, river dolphin

definition of ecology by Haeckel

oikos (greek)- house; the study of interactions between organisms and the environment, defined by Haeckel

Krebs definition of ecology

the study of interactions that determine the distribution and abundance of organisms

Townsend, Harper and Begon definition of ecology

the scientific study of the distribution and abundance of organisms and the interactions that determine distributions and abundances

distribution

where organisms occur and why

abundance

how many organisms there are in a particular location

interactions

how and why does an organisms interactions with other organisms and with its environment affects its distribution and abundance

studying ecology of individuals

how do they adapt to or deal with changes in their environment

studying ecology of populations

ecology of groups of organisms belonging to the same species

studying ecology of communities

ecology of populations belonging to different species

studying ecology of ecosystems

ecology of communities plus environmental effects

studying ecology of ecosphere

interactions among living and non-living factors across the whole earth

two ways to describe a population’s distribution

1. extent of the habitat over which an organism occurs
2. where individuals occur within a population

kinds of biomes

aquatic, desert, forests, grasslands, tundra

three common distribution patterns among individuals within a population

random, regular, clumped

random distribution

each individual is equally likely to occur anywhere, there are no strong effects of competition or the environment on the distribution

regular/uniform distribution

each individual is uniformly spaced within the population, this can be due to competition among individuals for resources or to some regularity in the distribution of resources

clumped distribution

individuals occur in high density patches, separated by areas with few individuals; can be due to mutual attraction among individuals or attraction to a common resource

measuring abundance

total number of individuals, density = number of individuals divided by unit area (volume)

typically we ________ abundance rather than count every individual because….

estimate; too hard to catch or find all individuals, too time-consuming to count all, too expensive to count all

space based methods

divide the population into equal sized areas/volumes, used for less mobile organisms

mark recapture methods

used for mobile organisms

why do we try to estimate population sizes

we would like to know how populations change in size overtime

problems with exponential growth

population increases forever

logistic growth equation

N=rN (1-N/K)

equation for population size

Nfuture= Nnow + B-D+I-E

Nnow

the population size now

Future

the population size in the future

B =

there number of births between now and the future

D =

the number of deaths between now and the future

I =

the number of immigrants. between now and the future (individuals entering population)

E=

the number of emigrants between now and the future (individuals leaving the population)

change in population size (from time now to time in future) is equal to the

difference between the number of births and the number of deaths

B>D

population size goes up

B

population size goes down

birth and death rates equation per individual

N = (b –d)N

what does r stand for in rN

the intrinsic rate of population increase or population growth rate

if r>0

population grows

if r

population shrinks

K=

carrying capacity, maximum population size a habitat can hold

growth is nearly exponential at

low population size

growth is very slow at

high population size

the logistic equation is more

realistic and suggests that populations cannot grow indefinitely but will instead reach some maximum size

extrinsically controlled growth reproductive strategies (r-strategy)

short life, rapid growth, early maturity, many small offspring, little parental care or protection, little investment in individual offspring

intrinsically controlled growth reproductive strategies (k-strategy)

long life, slower growth, late maturity, fewer large offspring, high parental care and protection, high investment in individual offspring

life table

look at population growth in some more detail, divides the population into distinct groups (ages or stages)

what is the most common life table

cohort table - follow all offspring born at a given time from birth until the last individual

what information can you get from a life table

population age structure

population growth rate

population survivorship patterns

life table variables

x

nx

lx

bx

x=

the age or stage

nx=

the number of individuals in each age/stage

lx=

the percent of the original cohort that survives to age/stage x

bx=

the number of offspring produced per individual in age/stage x

If we add up all the values of in the lxbx column we can obtain the

net productive rate or R

survivorship curve

a plot of the x values on the horizontal axis and the lx values on the vertical axis in a life table

Type I survivorship curve

occurs when the most mortality occurs late in life

Type II curve

occurs when mortality is spread equally across different stages

Type III curve

occurs when most mortality occurs very early in life

the demographic transition hypothesis

human societies tend to follow a pattern in population growth as they become more advanced

stage 1 of the demographic transition hypothesis

high but nearly equal birth and death rates, r is low

stage 2 of the demographic transition hypothesis

death rates decline but birth rates stay high, since b>d population increases

stage 3 of the demographic transition hypothesis

death rates decline as well but b is still > d

stage 4 of the demographic transition hypothesis

low but nearly equal birth and death rates, so r is low

fully domesticated mammals have undergone parallel changes

increased color variability

pedomorphosis (retain juvenile traits)

brain reduction

docility

earlier maturation

Who proposed that there were stages in the domestication of a species

Zeuner (1963)

Stages in the domestication of a species

loose ties, captivity, intentional breeding, planned development, elimination of the wild species as competitors

habitat

the physical area in which an organism lives

niche

a description of all factors which influence an organisms’s growth, survival, and reproduction

fundamental niche

any set of conditions under which an organism can occur and survive

realized niche

the conditions under which an organism really does occur

the fundamental niche is always

as large or large than the realized niche

neutralism

effect on x= 0

effect on y= 0

amensalism

effect on x= 0

effect on y= -

commensalism

effect on x= +

effect on y=0

competition

effect on x=-

effect on y=-

mutualism

effect on x= +

effect on y=+

predation or parasitism

effect on x= +

effect on y=-

definition of competition

an interaction between individuals for a shared resource in limited supply which leads to a reduction in survivorship, growth, or reproduction for at least one of the individuals, cost for both

contest competition

individuals fight for access to a resource, may involve direct contact or just threats

scramble competition

individuals do not directly interact, try to get resources more quickly than others do