Final Exam part 3 Flashcards
What is biogeography?
variation in species diversity and distribution across space
Biogeographic patterns are influenced by __________.
history, evolution, climate, physiology, and local interactions
_________ and _______ are the primary drivers of global species distributions.
temperature, and precipitation
Precipitation varies by _______.
Latitude
Species diversity varies by ________.
latitude
Why are the tropics more diverse?
- more solar energy
- niche conservatism
- lack of seasonality
- higher diversification
Historical biogeography studies how _____________.
past environmental factors have shaped current species distributions
What is the continental drift per year?
2.5 centimeters (1 inch)
Biogeographic regions correspond to __________.
Earth’s tectonic plates
Continental drift has resulted in unique ____________.
flora and fauna across continents
Biogeographical patterns in species distribution can occur due to _________.
past vicariance or dispersal
What is species-area relationship?
larger regions support more species
Why do larger regions support more species?
more niche space, larger population sizes leads to lower extinction rate
Smaller land areas have _______ species.
less
Species richness can be affected by (besides size) ___________.
distance from a source of species
What is the equilibrium theory of island biogeography?
Uses an area’s size and distance to a source population to determine species richness
The number of species on an island depends on. balance between ____________.
Immigration rates and extinction rates
What is an equilibrium number of species?
the number of species that should theoretically “fit” on an island
The equilibrium theory of island biogeography can be used to predict _____________.
The regional species pool of many habitats (not just islands)
When was the origin of life?
3.4-3.8 billion years ago
What was the Precambrian?
interval between the formation of Earth 4.6 billion years ago and the appearance of most animal groups 541 million years ago
What were the key developments of the precambrian?
liquid water, life, photosynthesis, oxygen atmosphere
Life was exclusively _______ for most of Earth’s history.
unicellular
What photosynthetic bacteria was responsible for the creation of the oxygen rich atmosphere?
Cyanobacteria
What was the Phanerozoic eon?
The interval between 541 million years ago and the present
What are the three domains of life?
bacteria, archaea, and eukaryotic
Archaea are ______ closely related to eukaryotes than bacteria
more
When did bacteria emerge?
3.5 billion years ago
When did archaea emerge?
approximately 3 million years ago
When did eukaryotes emerge?
1.2 billion years ago
Bacteria, archaea, and eukaryotes are all ______________.
monophyletic groups
Bacteria and most archaea are __________.
prokaryotes
What are prokaryotes?
cells that lack a membrane bound nucleus
Eukaryotic organisms have cells that have a ______________ nucleus.
membrane-bound
Eukaryotes can be ___________ or _________.
single, multicellular
Most Eukaryotic organisms are ___________.
protists
What is a microbe?
microscopic organisms
Bacteria and archaea are __________ and _________.
prokaryotes, microbes
The majority of bacteria are ____________.
Unnamed and undescribed
Lineages are of bacteria and archaea are _____, __________, _________, and _______.
ancient, diverse, abundant, and ubiquitous
How long were prokaryotes the only form of life on earth?
1.9 billion years
Bacteria and archaea are the __________ life-forms on earth today.
dominant
Where can bacteria and archaea be found?
almost everywhere (diverse habitats)
What is a microbiome?
the community of microbes that inhabits a particular area
What are extremophiles?
bacteria and archaea that live in high-salt, high-temperature, low-temperature, or high pressure habitats
Why are extremophiles a hot area of research?
- help us understand the origin of life
- explorations in extraterrestrial life
- commercial applications
Where do chemoorganotrophs get their energy from?
organic molecules
Where do chemolithotrophs get their energy from?
inorganic molecules
Bacteria and archaea are ____________ diverse.
morphologically
How are bacteria and archaea morphologically diverse?
size, shape, and mobility
What is cyanobacteria?
photosynthetic bacteria, first organism to perform photosynthesis, origin of oxygen in the atmosphere, origin of chloroplast
When did cyanobacteria evolve?
2.5-2.7 billion years ago
How does bacteria play a role in nitrogen fixation?
provides usable nitrogen for plants to incorporate into biomass
What are the key differences between bacteria and archaea?
- Bacteria have peptidoglycan in their cell wall
- Machinery used in the central dogma in archaea are more like those in eukaryotes than bacteria
- Bacteria are often pathogenic
What are pathogens?
bacteria that can cause disease
What is virulence?
the ability to cause disease
Virulence is a _________ trait.
heritable
What do antibiotics do?
kill bacteria or stop them from growing
Why do some bacteria and fungi naturally produce antibiotics?
to reduce competition
Antibiotics usually target the ___________.
cell wall
What does gram stain do?
distinguishes between two general types of bacteria
What does gram-positive mean?
Plasma membrane surrounded by a cell wall with extensive peptidoglycan
What does gram-negative mean?
plasma membrane surrounded by a cell wall with peptidoglycan and an outer lipid layer
Gram-negative bacteria are often more _______________.
virulent and difficult to treat
What is a virus?
an obligate, intracellular parasite that causes disease and must replicate within a host
Viruses are not __________ and are not made up of _______.
cells, cells
Viruses cannot manufacture their own ______, _______, or ________.
ATP, amino acids, nucleotides
Viruses do have _______.
hereditary material
What are two common morphologies of viruses?
Genetic material enclosed by a protein capsid or genetic material enclosed by a capsid and a membrane envelope
What are the steps of viral replication within a host?
- Viral genome enters a host bacterial cell
- Viral genome is transcribed; viral proteins are produced
- Viral genome is replicated
- Particles assemble inside host
- Particles exit to exterior
- Free virions in tissue or environment are transmitted to new host
Viruses are always made up of _____ and _____.
protein, genetic material
Are viruses organisms?
No
What are the requirements of life?
- consists of cells
- replicates
- contain hereditary information
- acquire and use energy
- product of evolution and evolves today
Why do researchers construct phylogenetic trees for specific lineages of viruses?
To understand the origin and emergence of new diseases
Viruses are grouped by ________.
genetic material
What are viruses further classifies by?
- virion and genome morphology
- nature of host species
- how the virus replicates in the host
What kind of virus is Covid?
ssRNA (single stranded)
Viruses from the same lineage can have different ______ and cause different types of _______.
hosts, diseases
Viral evolution can be very _______.
fast
What are the fundamental features of eukarya?
- most eukaryotic cells are larger than bacteria and archaea and have more organelles
- all have nuclear envelopes, the defining feature of eukaryotes
- multicellularity is rare in bacteria and archaea but has evolved multiple times in eukaryotes
- reproduce asexually through mitosis or sexually through producing gametes
How do bacteria and archaea reproduce asexually?
through fission
What were the features of the first eukaryote?
a single celled organism with mitochondria, and nucleus and membrane system, and a cytoskeleton but no cell wall
What were the first eukaryotes?
protists
What are protists?
all eukaryotes that are not plants, fungi, or animals
What occurs in mitochondria?
cellular respiration
How did mitochondria originate?
Via endosymbiosis when a bacterial cell took up residence within another cell 2 billion years ago
Mitochondria replicate by _____ and _______ is independent of division by the host cell.
fission, duplication
Mitochondria have their own ______ and manufacture some of their own _______.
ribosomes, proteins
Mitochondria have _________.
double membranes
Mitochondria have their own ________, which are circular
genomes
How did chloroplasts originate?
Via endosymbiosis when a protists engulfed a cyanobacteria
What led to chloroplasts in other lineages?
secondary endosymbiosis
How did the nuclear envelope originate?
Via infoldings of the plasma membrane
Why was the nuclear membrane favorable?
it separated transcription and translation
Chloroplast of some algae have an _____ ______ that contains _______ which supports the endosymbiosis theory.
outer layer, peptidoglycan
Why are protists paraphyletic?
They have no defining feature that is only found in protists and no other organisms.
Protists tend to live in habitats where they are surrounded by _______ most of the time.
water
What is a life cycle?
The sequence of events that occur as individuals grow, mature, and reproduce.
Protist reproduce asexually via _________ and sexually through ________.
mitotic division, meiotic cell division
Many single celled protist spend their life in either _______ or _______ form.
haploid, diploid
What form do most multicellular protist spend their life cycle in?
alternating between haploid and diploid
What is a sporophyte?
A diploid form that produces haploid spores through meiotic cell division
What is a gametophyte?
A haploid form that produces gametes through mitotic cell division
What is a spore?
A single haploid cell that divides mitotically to form a multicellular gametophyte.
What is a gamete?
A single haploid cell that fuses with another gametes to produce a diploid sporophyte.
Many protists are _____ because they have evolved structures for _________.
mobile, movement
Can protists be heterotrophs, autotrophs, or both?
both
What is phagocytosis?
The process of ingesting food much larger than individual molecules
How do protists consume bacteria, archaea, and other protists?
Through ingestive feeding (feeding through phagocytosis) or absorptive feeding (taking nutrients up directly from the environment)
Some protists have __________ for support or protection.
external shells
Some protists ______ humans.
parasitize
______ is one of the world’s most deadly infections, which is caused by a protist (Plasmodium)
Malaria
Harmful ________ can release toxins that accumulate in shellfish and harm people.
algal blooms
What are dinoflagellates?
photosynthetic protists
What is phytoplankton?
Photosynthetic protists that drift in open oceans and lakes. Basis of the food chains and freshwater and marine environments
What is zooplankton?
Drifting organisms, usually microscopic, that feed on phytoplankton
What is kelp?
a multicellular brown algae (protist)
Land plants evolved from an ancestral protists in the _____ _____ lineage.
Green algae
green algae are the closest living relative to land plants and form a ______ _________ with them.
monophyletic group
What led to the diversification of terrestrial life?
When land plants diverged from green algae approximately 475 million years ago
What are the defining characteristics of plants?
- Multicellular, eukaryotic organisms
- Cell walls made of cellulose
- Specialized reproductive organs
- Have chloroplasts and almost all perform photosynthesis
Why did plants transition to land?
Land offers plants resources like more light and carbon dioxide (new niches)
What adaptations prevented water loss when plants transitioned to land?
cuticle and stomata
What is a cuticle?
Waxy, watertight sealant that covers the above ground parts of plants.
What are stomata?
An opening surrounded by specialized guard cells that can open and close to prevent water loss and allow the exchange of carbon dioxide
Stomata close in _____ __________ and at _____ to prevent water loss.
dry conditions, night
Stomata open in ____ _______, allowing the uptake of carbon dioxide.
wet conditions
What adaptation provided protection from harmful UV radiation when plants transitioned to land?
Flavonoids
What are flavonoids?
UV-absorbing compounds which accumulate on plants and act as sunscreen for leaves and stems
What adaptation allowed land plants to move water from tissues with direct access to it to tissues without direct access?
Vascular system
What does the vascular system do?
Transports water from roots to above ground systems
The evolution of _____ drove the evolution of the vascular system by providing ______ _______ for plant tissues, allowing upward growth.
lignin, structural support
What do tracheids do?
Allowed for more efficient water transfer through gaps in the secondary lignin wall.
What do vessel elements do?
Reduce resistance and make water movement more efficient to create a continuous pipe-like structure.
In what order did the vascular system evolve?
- Simple water conducting cells
- First vascular tissue (found in fossils)
- Tracheids (found in vascular plants)
- Vessel elements (found in gnetophytes and angiosperms)
What are the four groups of land plants ?
- Nonvascular plants
- Seedless plants
- Gymnosperms
- Angiosperms
What are the characteristics of nonvascular plants?
Lack of a vascular system, low sprawling growth habit, anchor to substrate using rhizoids, grow in moist habitats, depend on water for reproduction
Do nonvascular plants have stomata or cuticles?
No, they live in moist environments.
What types of plants are nonvascular plants?
liverworts, mosses, and hornworts
What are the characteristics of seedless plants?
Conducting tissues with cells reinforced by lignin, depend on water for reproduction
What types of plants are seedless?
ferns, club mosses, and horsetails
The evolution of ______ and _______ allowed for reproduction on dry land.
seeds, pollen
What is pollen?
A male gametophyte surrounded by a protected coat to prevent drying.
What are seeds?
A zygote produced by fertilization, surrounded by a protective coating.
What do seeds allow for?
Nourishment of zygotes and for offspring to disperse form parents
The evolution of pollen an seeds led to a ______ __ _____ _____ about 365 million years ago.
radiation of seed plants
________ produce seed and pollen grains, but do not produce flowers.
Gymnosperms
What plants are examples of gymnosperms?
Palms and evergreens
What is a flower?
A reproductive organ
What is the stamen?
The male reproductive organ of a flower where meiosis occurs, producing pollen grains.
What does the stamen consist of?
Anther and filament
What is a carpel?
The female reproductive organ of a flow in which meiosis occurs to produce eggs.
What does the carpel consist of?
Stigma, style, and ovary
The evolution of flowers allowed for the evolution of _____.
fruit
Fruits increase _____.
dispersal
What is fruit?
A structure that develops an ovary and contains one or more seeds
What are angiosperms?
flowering plants
What is adaptive radiation?
A single lineage produces a large number of descendent species adapted to a wide variety of habitats.
The evolution of flowers led to an _______ _________.
adaptive radiation
What are angiosperms traditionally split into?
monocots and dicots
What is the issue with just classifying angiosperms as monocots and dicots?
Dicots are not a monophyletic group, so they were reclassified as edicots and magnoliids
All plants show __________ __ __________.
alternation of generations
What is the nonvascular life cycle dominated by?
gametophytes
What life cycle came first: sporophyte-dominant or gametophyte-dominant?
gametophyte-dominant
What types of plants spend much of their life as sporophytes and have complicated reproductive structures?
Angiosperms and gymnosperms
Why did sporophyte-dominant life cycles evolve?
Sporophyte-dominant life cycles were advantageous because diploids can respond to varying environments more efficiently (more genetic diversity)
What two things did seeds and pollen allow for?
reproduction on dry land and dispersal
What did specialized reproductive organs allow for?
Embryos to be nourished by the parent plant
What stage does dispersal occur in: haploid or diploid?
diploid
What are the benefits of seed dispersal?
reduced competition, new niches, and no reliance on water
What allowed for the evolution of animal pollination?
Flowers
What is pollination?
The transfer of pollen from one plant’s stamen to another plant’s carpel
What is the directed-pollination hypothesis?
Natural selection has favored flower scents, shapes, and colors that attract particular types of pollinators
What are the benefits of pollination?
cross fertilization (increases genetic diversity, reduces inbreeding) and increased gene flow
What determines the energy available to other organisms?
plant community structure
Plants make life on earth ______.
possible
Plants provide ________ _________.
Ecosystem services
What are fungi?
Eukaryotes that occupy terrestrial environments
Are fungi autotrophs or heterotrophs?
Heterotrophs
How do fungi get their energy?
They release their digestive enzymes into the external environment to absorb small molecules
Many fungi live in ________.
symbiosis
Fungi are both _______ and _________.
parasitic, mutualistic
Are fungi more closely related to land plants or animals?
Animals
What key morphological traits do fungi and animals share?
- synthesize chitin
- Flagella of spores and gametes are similar to those observed in animals
- Both store food to make glycogen
What is chitin?
A tough, structural material
What two growth forms do fungi exhibit?
Yeasts and mycelia
What are yeasts?
single- celled forms
What is mycelia (mycelium)?
Multicellular, filamentous structures
Why are mycelium dynamic?
They grow in the direction of food sources and die back in areas without food
When does the body shape of fungus change?
Almost continuously throughout its life
What adaptation supports the external digestion and absorptive lifestyle of fungi?
Mycelium
What are hyphae (singular form: hypha)?
The filaments making up a mycelium
Most hyphae are divided into cell walls called _________, which gaps for exchange of materials.
septa
What are coenocytic hyphae?
Hyphae with no septa and the nuclei are scattered across the mycelium
Do fungi have long distance transport systems?
No
Why are mycelium highly efficient at absorbing nutrients?
They are thin, branching networks (high surface area: volume ratio)
Where are fungi most abundant and why?
Moist habitats because they dry out easily
Spores are resistant to ______.
drying
Fungi reproduce using ______.
spores
What are conidia?
asexual spores produced by mitosis from haploid mycelium
What are mating types?
genetically distinct hypha from different individuals
What is plasmogamy?
When hyphae from two different mating types grow near each other and fuse to form a hybrid cell
What is a heterokaryotic mycelium?
When two different mating types are in one mycelium
What is karyogamy?
When in a heterokaryotic mycelium, pairs of unlike nuclei fuse to produce a diploid nuclei (zygote)
What happens after karyogamy?
The diploid zygotę divides via meiosis to produce haploid spores (genetically distinct)
What form do most fungi spend the majority of their life cycle in: haploid, diploid, or heterokaryotic?
haploid
What are the reproductive structure of fungi made of?
Hyphae (the only part of the fungus exposed to air)
Do hyphae absorb food?
no
What are the four key types of sexual reproductive structures in fungi?
- swimming gametes and spores
- zygosporangia
- basidia
- asci
What are chytrids and where do they primarily live?
Species with swimming gametes, primarily in water and wet soils
What are zygosporangia?
Spore producing structures formed when hyphae are yoked (Haploid hyphae from two individuals meet and become joined in a spore producing structure)
What are species with zygosprangia called?
zygomycetes
Is the zygomycete life cycle primarily haploid, diploid, or heterokaryotic?
Haploid
What are basidia?
Club-shaped cells at the end of the hyphae where meiosis occurs, forming 4 spores (mushrooms, brackets, and puffballs)
What are species with basidia called?
basidiomycetes or “club fungi”
Do basidiomycota spend their life cycle primarily haploid, diploid, or heterokaryotic?
haploid
What are asci?
sac-like cells at the end of the hyphae where meiosis and one round of mitosis occurs, forming 8 spores.
What are species with asci called?
ascomycetes or “sac fungi”
Do ascomycota primarily spend their life cycle in diploid, haploid, or heterokaryotic form?
haploid
Fungi lineages are linked to production of different ______________ __________.
reproductive structures
Which two groups of fungi collapsed into a polytomy?
chytrids and zygomycetes
Which groups of fungi are monophyletic groups?
glomeromycota, basidiomycota, and ascomycota
What are saprophytes?
Fungi that digest dead plant material
Why are fungi efficient decomposers?
- Extracellular digestion
- Breakdown of lignin
- Fungi can digest cellulose
How do saprophytic fungi impact the terrestrial carbon cycle?
They release the carbon stored in the lignin of plants
Decomposers release useable ______ and ________ from dead organisms back into the soil.
nitrogen, phosphorous
What are microsporidia?
A lineage of parasitic fungi
Parasitic fungi can effect ______ and threaten ____ __________.
humans, crop production
What are mycorrhizae?
Fungi that live in close association with plant roots (mutualistic). Fungi benefit through nutrients received from the plant, plant benefits because the fungi release nitrogen and phosphorous back into the soil.
What are endophytes?
fungi that live between and within plant cells (mostly mutualistic)
What are the key traits shared by all animals?
- Multicellular eukaryotes whose cells lack a cell wall
- Heterotrophs
- Move under their own power at some point in their life
- Have nerve cells and muscle cells (except sponges)
When did the radiation of animals begin?
550 million years ago during the Cambrian explosion
Common ancestor to animals evolved about ________ million years ago. The first animal appear about _______ million years ago.
800, 700
What were the first animals?
early sponges
What caused the Cambrian explosion?
- Higher oxygen levels
- Rise of algae
- Evolution of predation
- New niches beget more new niches
How many phyla of animals do biologist recognize?
30-35
What are the key themes in animal evolution?
- evolution of animals is more complicated than a smooth transition from simple to complex
- many key innovations did not arise at once
(“deep homology” followed by homoplasy) - evolution did not stop within any of the lineages
How can we study the evolution of animals?
- comparison of body plans
- comparison of developmental processes
- comparative genomics
- the fossil record
What is epithelium?
A layer of tightly joined cells that cover the exterior and/or interior surface of animals
What necessary genes do sponges have that are used animals for development?
- specialization of cell types
- regulation of cell cycling and growth
- developmental signaling and gene regulation
- programmed cell death
- recognition of self and non-self
What genes for contractile proteins do sponges have?
actin and myosin
What are diploblasts?
Two types of embryonic tissue
What is endoderm?
Inner layer that gives rise to the lining of the digestive tract
What is the ectoderm?
Outer layer that gives rise to the skin and nervous system
What are triploblasts?
three types of embryonic tissue
What is the mesoderm?
Middle layer that gives rise to the circulatory system, muscle, and internal structures
What are the three major animal groups?
Non-bilateral phyla, protostome phyla, and deuterostome phyla
What are characteristics of the non-bilateral phyla?
Radial and diploblastic. Use a hydrostatic skeleton ( tissue supported by fluids)
What are characteristics of the protostome phyla?
bilateral and triploblastic
What are characteristics of the deuterostome phyla?
bilateral and triploblastic
Bilateral symmetry is linked to the development of a _____ _______ and ______________.
nervous system, cephalization
What is a coelom?
An internal, usually fluid filled body cavity lined with mesoderm (synapomorphy of bilateral lineages, but lost in some lineages)
What is segmentation?
The division of the body or part of the body into a series of similar structures
What are characteristics of invertebrates?
no backbone, segmentation in body plan
What is another name for the protostome phyla and why is it called that?
“first mouth” named after the embryonic development of the mouth before the anus
What is another name for the deuterostom phyla and why is it called that?
“second mouth” named after the embryonic development of the anus before the mouth
The vast majority of animals are _________.
protostomes
What is important about arthropods?
They are the most abundant and diverse animals observed in both aquatic and terrestrial ecosystems
What are the three key features that characterize arthropods?
- segmented body
- an exoskeleton
- joint appendages
What is an exoskeleton?
hard external skeleton made of chitin
What are joint appendages?
joints between segments and the legs
Insects have ________ and __ ___.
wings, siz legs
Insects are diverse and abundant and play crucial roles in _______ and ______ ecosystems.
aquatic, terrestrial
What are the four key requirements of chordates?
- pharyngeal slits or pouch
- dorsal hollow nerve chord
- notochord
- a muscular, post-anal tail
What are vertebrates?
organisms that have a vertebrae and a cranium
What is a vertebrae?
a column of cartilaginous or bony structural support
What is a cranium?
a bony, cartilaginous, or fibrous case that encloses the brain
What were the early key innovations of vertebrates?
jaws, lungs (lost in sharks & rays and coopted into swim bladders in ray-finned fishes), and bones
What are bones?
dense tissue consisting of cells and blood vessels in a matrix of calcium that form an endoskeleton in vertebrates
Evolution of limbs allowed the __________.
transition onto land
What was the “Limbs from Fins Hypothesis”?
The fossil record links the limbs of the ancestors of today’s lungfish to those of the earliest land-dwelling vertebrates
What are tetrapods?
organisms with two pairs of limbs
Why were tetrapods a key morphological innovation?
They allowed vertebrates to exploit the ecological opportunities of the terrestrial environments, leading to diversification
What are amphibians?
the first tetrapods to live on land (adults feed on land but lay their eggs in water)
what does ectothermic mean?
individuals do not use their internally generated heat to regulate their body temperature
What did amniotes allow for?
allowed for reproduction on land
What is an amniotic egg?
Eggs that have a protective covering that reduces the rate of drying, allowing species to lay them outside of water
Are reptiles more closely related to amphibians or mammals?
mammals
What is an endotherm?
organisms that regulate their body temperature with energy produced internally
Mammals have _______ and _____.
lactation (mammary glands), fur
What is lactation?
The production of milk which nourishes offspring
Mammals are the only vertebrate group with _____ ________ and _____ which makes suckling possible.
cheek muscles, lips
Hair is primarily made of _____.
Keratin
What contains the amniotic egg in most mammals?
The placenta
What is the placenta?
An organ containing maternal and embryonic tissues, provides oxygen and nutrients to the developing embryo
What are the benefits of the placenta?
- Offspring develop at a more consistent temperature
- Offspring are protected
- Offspring are portable
What lineage are humans a part of?
Primate
Humans evolved from the common ancestor of all ______ animals.
placental
What are the traits of primates? (6 of them)
- Hands and feet that are efficient at grasping
- Flattened nails instead of claws
- Brains that are large relative to body size
- Color vision
- Complex social behavior
- Extensive parental care
Humans are the only living hominid that is fully ____.
bipedal
What is bipedalism?
The ability to walk upright on two legs
Humans share ____ of our genome with chimpanzees.
95%
When did humans begin to split off from chimpanzees?
6 million years ago
What percentage does the brain make of body mass in Humans and what percentage of energy does it use?
2% of mass, 20% of energy
Approximately when did Homo sapiens evolve?
300,000 years ago
How much of the human genome is of Neanderthal origin?>
4%
Why did the Neanderthals go extinct?
- Inbreeding, causing a decline in genetic diversity
- Climate change and competition for resources with humans
- Humans had more complex social behaviors
- Hybridization between Neanderthals and humans
- Conflict between Neanderthals and humans
What did the rise in human populations cause?
global change
What is the current population of Humans on Earth?
Approximately 8 million
What type of population growth curve does the human population represent?
density independent, exponential
Will humans reach density dependent growth and overshoot carrying capacity?
Yes, if populations growth rate does not decline more.
Is population growth rate in Humans currently declining or growing?
declining
What is fertility rate?
Average number of surviving children that a woman has in her lifetime
What fertility rate would result in a population growth rate of zero?
2
What is the current fertility rate?
2.5
What will the population reach if the growth remains the same?
nearly 17 billion
What will the population reach if if the growth rate reaches 2?
A little over 11 billion
What was the growth rate in the 1950’s?
5
What are endangered species?
Species whose number has decreased such that it will go extinct without conservation action
Rate of species extinctions are increased with rapidly growing _____ ________.
human populations
What threats from human activities act on species endangerment/ extinction?
- Habitat destruction and degradation
- Overexploitation
- Invasive species and disease
- Pollution
- Climate change
