X - Population Dynamics, Carrying Capacity, & Conservation Biology Flashcards
Population dynamics
Changes in population size, density, dispersion, & age
distribution
Characteristics of Populations includes
Population size
Population density
Dispersion
Age structure
Population size
number of individuals in a population at a given time
Population desnity
number of individuals per unit area in terrestrial ecosystems or per unit volume in aquatic ecosystems;
Dispersion
spatial patterning individuals
Age structure
proportion of individuals in each age group (e.g., prereproductive, reproductive, & post-reproductive) of a population
In terms of dispersion, individuals of a population can be
Clumped
Uniform
Randomly distributed
Population size is governed by
births, deaths, immigration, and emigration
[Population Change] =
[Births + Immigration] – [Deaths + Emigration]
Zero population growth occurs when
the number of individuals added by births & immigration are balanced by those lost by deaths &
emigration
Biotic potential
a population’s capacity to grow
intrinsic rate of growth (r)
the rate at which a population will grow if it had unlimited resources
Biotic growth factors
High reproductive rate Generalized niche Adequate food supply Suitable habitat Ability to compete for resources Ability to hide from/defend against predators Ability to resist diseases & parasites Ability to migrate & live in other habitats Ability to adapt to env'tal change
Abiotic growth factors
favorable light
favorable temperature
favorable chemical env’t
Biotic decrease factors
low reproductive rate specialized niche inadequate food supply unsuitable habitat inability to compete for resources inability to hide from/defend against predators inability to resist diseases & parasites inability to migrate & live in other habitats inability to adapt to env'tal change
Abiotic decrease factors
Too much/ little light
Temp too high/low
Unfavorable chemical env’t
carrying capacity (K)
the number of individuals that can be sustained in a given space
if the carrying capacity for an organism is
exceeded,
resources are depleted, environmental degradation results, & the population declines
Exponential growth occurs when
resources are not limiting.
Logistic growth occurs
when
resources become more and more limiting as population size increases.
During exponential growth,
population size increases faster & faster with time
Currently the human population is…
undergoing exponential growth
exponential growth can not occur forever because
eventually some factor limits population growth
when the population is small the logistic population growth
curve looks like
exponential growth
What occurs when the carrying capacity is exceeded?
“overshoot” was followed by a “population crash”.
Numbers then stabilized, with oscillation about the carrying capacity.
Stable populations
Relatively constant over time
Cyclic curves
often associated with seasons or fluctuating resource availability
Irruptive curves
characteristic of species that only have high numbers for
only brief periods of times (e.g., seven–year cicada)
Two categories of strategies
r-strategist
K-strategist
r–strategist species
tend to live in recently disturbed (early successional) environments where resources are not limiting
such species tend to have high intrinsic rates of growth (high r)
K–strategist species
tend to live in environments where resources are limiting (later succession) & tend to have lower intrinsic rates of growth and characteristics that enable them to live
near their carry capacity (population size near K)
Characteristics of
r–strategists
production of many small & unprotected young, enable
these species to live in places where resources are
temporarily abundant
typically “weedy” or opportunistic.
r-strategist example
Cockroach
Dandelion
Characteristics of
K–strategists,
production of few large & well cared for young, enable
these species to live in places where resources are
limited
typically good competitors.
K-strategists example
elephants
saguaro
Types of survivorship curves
Late loss
Constant loss
Early loss
late loss
usually K–strategists high mortality is late in life
late loss examples
rhinos
humans
constant loss
mortality is about the same for any age;
Constant loss example
songbirds
early loss
usually r–strategists high mortality is early in life.
early loss examples
fish
frogs
Conservation biology
interdisciplinary science that deals with problems of maintaining Earth’s biodiversity, including genetic, species, & ecosystem components of life
Conservation
sensible use of natural resources by humans
Three underlying principles of conservation
- biodiversity & ecological integrity are useful & necessary for
life & should not be reduced by human activity; - humans should not cause or hasten premature extinction of
populations & species; - the best way to preserve biodiversity & ecological integrity
is to protect intact intact ecosystems & sufficient habitat.
Ensuring viable populations of wild species ultimately requires
protection of sufficient suitable habitat.
Habitat fragmentation
process by which human activity breaks natural ecosystems into smaller & smaller pieces of land
habitat fragments
Small islands of land caused by habitat fragmentation
One concern about remaining habitat is
Whether it is of sufficient size & quality to maintain viable populations of wild species
Corridors
long areas of land that connect habitat that otherwise would be fragmented
What is the importance of corridors?
corridors permit movement of migratory animals and ensure interbreeding of plant & animal populations
What is a criticism of corridors?
may be too narrow to be of value
Corridor example
corridor of protected land between protected
lowland rain forest of La Selva Biological Station, Costa
Rica, & mountain habitat of Braulio Carrillo National Park protects biodiversity by ensuring that species can migrate up & down the mountains
Bioinformatics
management of biological information.
What is bioinformatics important to conservation biology?
• good conservation biology requires good
information
• increasingly conservation efforts require building
computer databases concerning biodiversity
Major human impacts on ecosystems includes
• fragmenting & degrading habitat;
• simplifying natural ecosystems;
• strengthening some populations of pest species and
disease–causing bacteria by speeding natural selection
& causing genetic resistance through overuse of
pesticides & antibiotics;
• eliminating some predators;
• deliberately or accidentally introducing new species;
• overharvesting potentially renewable resources;
• interfering with chemical cycling & energy flows.
living systems have six key features
interdependence, diversity, resilience, adaptability, unpredictability, & limits;
Most ecosystems use
sunlight as major energy source
energy is always required to
produce or maintain energy flow or to recycle chemicals;
Ecosystems replenish
Ecosystems dispose
Nutrients
Wastes
In an ecosystem what are renewed?
soil, water, air, plants, & animals are renewed
complex networks of positive & negative feedback loops operate within
natural systems, whether in individual organism, populations, or whole ecosystems;
population size & growth rate of all species are controlled by
interactions with other species & the nonliving environment.
biodiversity takes forms of
genes, species, and ecosystems
our lives, lifestyles, & economies are dependent on the
sun and earth
we are part of, not apart from
Earth’s dynamic web of life
Global CPR
conservation
preservation
restoration
Can we restore damaged ecosystems?
In some cases
Natural restoration
Relatively slow
Repair & protect ecosystems
Considerable effort & expense
Requires solid understanding of ecology
Natural restoration example
in Sacramento, California, rancher Jim Callender restored a wetland by reshaping land and handplanting native plants; many of the native plants &
animals are now thriving there
It is not possible to undo all ecological harm
Such as in cases of extinction
