Interactions between individuals and species

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Interactions between individuals and species

• Name Nie Chengrong ???
• Cell telephone [phone]
• Email niecr_at_126.com

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Introduction

• Interactions between individuals and species can
  be classified on the basis of the effect and the
  mechanisms of the interaction.
• The key interspecific interactions are
  competition, predation, mutualism and
  commensalism.
• The main intraspecific interactions are
  competition, cannibalism and altruism.

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Pairwise species interactions
Influence of species A
0 (neutral/null)
- (negative)
(positive)



-
0
Influence of Species B

From Abrahamson (1989) Morin (1999), pg. 21
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Interspecies interaction

• Neutral interaction
• Positive interaction Commensalism, Mutualism,
  Protocooperation
• Negative interaction Competition, Predation,
  Parasitism, Parasitoids, Amensalism

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Intraspecies interaction

• Neutral interaction
• Positive interaction Altruism
• Negative interaction Competition, Cannibalism,
  Parasitism

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Populations may be linked by competition,
predation, mutualism and commensalism
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1 Competition

• Competition is an interaction among individuals
  utilizing a limited resource, resulting in
  reduced fitness in the competing individuals.
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• Competition occurs both between species utilizing
  a shared resource (interspecific competition) and
  among members of a species (intraspecific
  competition).
• ????????????????????,?????????????????

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????(intraspecific completion)

• Definition of intraspecific completion
• Competition occurring between members of the
  same species is defined intraspecific completion.
• As individuals among a species are quite similar
  in their resource requirements, so intraspecific
  competition may be particularly intense.
• ?????????????????????????????,??????????????????,?
  ??????????

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????(intraspecific completion)

• Intraspecific competition is a major force in
  ecology and is responsible for phenomena such as
  dispersal and territoriality, as well as being
  the primary cause of population regulation via
  density-dependent processes.
• ??????????????????????????????????????????,???????
  ???????????,???????????????????????????????,???(d
  ispersal)????(territorality)?

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Density dependence????

• Density dependence describes the relationship
  between fitness and population size. A key
  population regulatory factor is negative density
  dependence, where declining fitness occurs as
  population density increases within a species due
  to intraspecific competition
• ??????????????????????????????????????????????????
  ?,??????,??????????

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• Scramble competition(????) resources
  distribution within a species may be fairly even,
  so that most individuals get a similar amount of
  food. Under high density no individuals gets
  enough to survive and the population crashes.
  ????????????,??????????????????????,??????????????
  ,???????(p98).
• Contest Competition (????)In some species high
  density result in a very uneven distribution of
  resources so that some individuals grow and
  reproduce whilst other die.

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Interspecific competition

• Definition of interspecific competition
• Competition occurring between two species using
  the same limited resource is defined
  interspecific competition.
• When resources are in short supply, interspecific
  competition for resources may occur.
• Very few species can escape from the effects of
  other species competing for the same resource. So
  there is potential for competition between any
  two species that need the same limited resource.

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????(interspecific completion)

• When two species share a limited resource
  interspecific competition occurs.
  ??????????????,????????????????????(Paramecium
  aurelia)?????(P.Caudatum)?????????????,P.aurelia
  ?P.Caudatum????????????????,P.aurelia???,??P.Cauda
  tum?????

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Example of interspecific completioninvasive weed

• Exotic plants occasionally become troublesome
  weeds because of their vigorous competitive
  ability, allowing them to exclude a broad
  spectrum of native plant species in a particular
  habitat.

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Operating ways for competition???????

• Exploitation competition(?????) Affecting each
  other indirectly, and just using the limited
  resources
• ?????????,?????????????????
• Interference competition (?????) Affecting each
  other directly ,and often having a fight
• ??????????????????????????????????????????????????
  ?????????????????,???????????????,????????????????
  ?????????(P96)?

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Competitive asymmetry?????????

• Competition often unevenly affects competitors,
  such that the cost for one individual is far
  greater than for another. It is common for
  competition to kill the losers, either via
  exploitation or interference.
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  ???????????????(p97) ??????
• ????????????,??????????
• ???????????????
• ?????????????,?????????

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The competitive exclusion principle??????

• The competitive exclusion principle two species
  with similar needs for same limiting resources
  cannot coexist in the same place.
• Where two species compete in a stable and
  homogeneous environment, either one species will
  win and the other be excluded, or both species
  will manage to coexist via niche divergence.
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  ????????????,?????????????????????????

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Gauses competitive exclusion principle No two
species can coexist if they occupy the same
niche(???)
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• The ecological niche is the sum total of an
  organisms use of abiotic/biotic resources in the
  environment.
• An organisms niche is its role in the
  environment.
• The competitive exclusion principle can be
  restated to say that two species cannot coexist
  in a community if their niches are identical.

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• Classic experiments confirm this.

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• Resource partitioning is the differentiation of
  niches that enables two similar species to
  coexist in a community.

Fig. 53.2
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Example of interference completionALLELOPATHY

• ALLELOPATHY
• In plant species, the process of competing via
  toxin production is termed allelopathy.
• Allelopathy is a phenomenon of chemical
  regulating and controlling in natural ecological
  system and is a mechanism of organisms adapting
  to environment.

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2 Predation

• Definition of predation ?????
• Predation can be defined as the consumption of
  all or part of another individual (the prey).
• ????????????(??)?????????

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• Predation.
• A predator eats prey.
• Herbivory, in which animals eat plants.
• In parasitism, predators live on/in a host and
  depend on the host for nutrition.
• Predator adaptations many important feeding
  adaptations of predators are both obvious and
  familiar.
• Claws, teeth, fangs, poison, heat-sensing organs,
  speed, and agility.

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This wide predation include 4 types???????????

• (i)True predatorskill their prey soon after
  attacking them???????????????????
• ???????????????????????
• (ii)Grazersconsume only part of a prey
  individual??????????????
• ?????????,?????????????????
• (iii) Parasites and Parasitoids, which live in
  very close association with a single prey
  individual (the host), often inside the hosts
  tissues?????????????????
• ????(????)?????(????)???????????
• (?) Cannibalism ?????????????,????????????????

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Categories of Predators??????

• (i) herbivores which consume plant tissue???
• (ii) carnivores which food in animal tissue???
• (iii) omnivores which feed on both plant and
  animal???
• The difference between animals and plants as prey
  types required different physiological and
  behavioral adaptations, and has lead to repeated
  evolutionary divergence between carnivorous and
  herbivorous lineages.
• ????????????????????????,?????????????????????????
  

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Predation- one organism kills and eats another
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Predation
Herbivory - animal eats a plant
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Categories of Predators

• Predators vary in the number of species of prey
  they will feed on, with some species being
  specialists, whilst others are more generalist.
  Generally, parasites tend to be more specialist
  than true predators and herbivores tend to be
  more specialist than carnivores.
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  ?????????????,??????
• Specialists?????????????????????Generalist?????
  ????????????
• ???,???????????????????????????

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The impact of predators on prey population
size?????????????

• Do predators and parasites regulate the
  population size of their prey? This is not as
  simple a question as it may appear. There are two
  main issues (I) the effect of any one predator
  may only be a small component of the total
  mortality causes affecting a prey species, so
  removal of the predator will have only a minor
  effect (ii) predation may kill animals which
  were going to die anyway, so there will be no
  impact on the final prey population size.
  However, in a number of cases there is clear
  evidence that predators have a considerable
  impact on prey numbers.
• ??????????????????????????????????????????????(i)
  ????????,???????????????,?????????????????(ii)???
  ?????????????????,??????????????????,????????,????
  ????????????

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Population Growth Patterns
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Predator behavior and prey response???????????

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  ???????,?????????,????????
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  ??????,??????????????????????????????????????

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Switching between prey types????

• Predators which may consume a number of prey
  species may partially specialize on the commonest
  prey type available at any one time and
  concentrate their attacks on this more common
  prey. If the relative abundance of prey species
  then change such that another species becomes the
  commonest, this species will now be the focus of
  more attacks. This process is known as predator
  switching.
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  ?,??????????,???????????????,????????????

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• Predators may alter or switch their preference
  for a particular prey species depending on the
  abundance of that species. When this occurs,
  common prey are consumed super proportionately
  whilst less common prey are largely ignored.
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  ??????
• This tendency to specialize suggests that there
  are the benefits to the predator possibly
  searching efficiency is increased if the predator
  has a single search image.
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Response of prey

• Species that tend to be eaten by either predators
  or herbivores have evolved their own defenses.
  Some animals are fast and can run away from
  predators. Others are effectively camouflaged
  (??) and can hide to avoid being eaten. Many
  animals and plants produce toxins, known as
  secondary metabolites, to discourage other
  animals from eating them. Poison arrow frogs,
  for instance, have toxins in their skin. Their
  bright coloration, called aposematic coloration
  (???), warns potential predators to stay away.
  Plants produce many toxic or distasteful
  chemicals to avoid being eaten.

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• Plant defenses against herbivores include
  chemical compounds that are toxic and defensive
  structures.
• Animal defenses against predators.
• Behavioral defenses include fleeing (??), hiding,
  self-defense, noises, and mobbing (????).
• Camouflage includes cryptic coloration (???),
  deceptive markings.

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• Mechanical defenses include spines(??).
• Chemical defenses include odors (??) and toxins
• Aposematic coloration (???) is indicated by
  warning colors, and is sometimes associated with
  other defenses (toxins).

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• Mimicry(??) is when organisms resemble other
  species.
• Batesian mimicry is where a harmless species
  mimics a harmful one.

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• Müllerian mimicry is where two or more
  unpalatable species resemble each other.

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Plant defense????

• Plants defend themselves from predation in two
  main ways
• (i) toxicity and unpalatablity,
• (ii) defensive structures.
• ??????????????????
• (i)???????
• (ii)?????

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toxicity and unpalatablity

• There is a vast variety of chemical ammunition
  found in the plant kingdom used to defend plants
  against attacks from predators and parasites.
  These secondary compounds may either be directly
  toxic or they may reduce the food value of the
  plant, for example, by reducing the availablity
  of the leaf tissue protein to the animal gut.
• ???????????????????????????????????????????????,??
  ?????????,???????????????????

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Defensive structures

• Defensive structures exist on a variety of
  scales, from small hairs on the leaf surface
  which may trap insects and other invertebrates,
  to large spines which deter mammalian herbivores.
  Both the levels of secondary compounds and the
  size of defensive structures may be elevated or
  induced in plants that have suffered
  defoliation.
• ?????????????,??????????????????????,?????????????
  ????????????,????????????????????????

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3 Parasites

• Parasitism is kind of interaction in which one
  species benefits to the detriment(??) of another.
  
• Parasitism(??)
• - one organism feeds from or benefits from
  another, at the others expense
• ??????????????????????????????????????????

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• Parasitism- one benefits, the other is harmed
• ticks(??) dogs
• tick gets nutrients from dogs blood
• dog gets sick from loss of blood
• also has other possible parasites transmitted
  from ticks
• Parasites usually harm but dont kill host
• If host dies then the parasite dies as well
• unless a new host is found

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• Parasite life cycles can be quite complex,
  involving several hosts to complete an entire
  cycle.
• For example the life cycle of Plasmodium, a
  protist that causes malaria in humans, involves
  two hosts, a human and a mosquito. The mosquito
  takes blood from a human carrying the Plasmodium
  parasite. The blood is filled with an early
  developmental stage of the parasite which begins
  to mature inside the mosquito. Once the
  parasites reach a certain stage, they are
  injected from the mosquito into a human.
  Plasmodium parasites fully mature within the
  human liver and are released in red blood cells
  where they reproduce asexually, causing a
  significant number of red blood cells to burst.
  Weakness ensues(????)and may lead to the death of
  the host.

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• Tapeworms(??) are another parasite with life
  cycles involving more than one host. Their eggs
  develop into larvae in the muscles of animals
  such as pigs and cattle. When humans eat
  undercooked meat, they may ingest the eggs and
  allow a tapeworm to take up residence in their
  intestines. Tapeworms absorb nutrients from the
  intestines, so the host is robbed of necessary
  nutrients. Parasitic survival does not generally
  lead to death, but weakness or behavior
  modification brought on by a parasite can lead to
  death for the host organism.

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Heterogeneity in host populations

• Individuals within a host population are very
  rarely equally at risk of being successfully
  attacked by a given parasite. The age, behavior,
  state of health, proximity of the infected
  individuals, and, of particular importance, the
  genetic predisposition of an individual will all
  influence the outcome.
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  ??????????????????,???????

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• Parasitoids (???)
• eggs laid inside host
• to kill eventually

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• Parasites and pathogens as predators.
• A parasite derives nourishment from a host, which
  is harmed in the process.
• Endoparasites live inside the host and
  Ectoparasites live on the surface of the host.
• Parasitoidism is a special type of parasitism
  where the parasite eventually kills the host.
• Pathogens are disease-causing organisms that can
  be considered predators.

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Amensalism(??)
Having bad effect to one and nothing to the other
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4 Mutualism and Commensalism

• Mutualism is where two species benefit from their
  interaction.
• Commensalism iswhere one speciesbenefits from
  theinteraction, but otheris not affected.
• An example wouldbe barnacles thatattach to a
  whale.

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• Mutualism
• Mutualism is a positive reciprocal(???)
  relationship between two individuals of different
  species which results in increased fitness for
  both parties. ????????????????????,??????????
• Mutualism is one kind of interaction that ends up
  being a win-win situation for both species
  involved. The interacting species benefit from
  this interaction and ultimately are better able
  to reproduce and continue as species.

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Mutualism(????)

• Facultative mutualism(????)(??) Both get
  benefits, but not depend each other. e.g.
  bee-plant
• Obligate mutualism(????)To depend each other and
  benefit each other. e.g. nodule-plant

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Facultative mutualism??????

• The majority of mutualisms are nonobligatory and
  opportunistic. They may be diffuse, involving a
  varying mixture of species, as occurs between
  many pollinators and their plants.
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  ???????????

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• Proto-cooperation????
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• ? ????(?),????????????,????????????,???????????,??
  ???????
• ? ?????????????,????????????????????????????

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Pollination??

• An out crossing plant needs to transfer its
  pollen to the stigma of a conspecific plant, and
  receive pollen from a conspecific. Some plant
  species rely on the wind to achieve this, which
  can work acceptably well if plants grow in large
  homogeneous stands of few species, as occurs in
  grasslands and pine forests, However, in most
  species of flowering dicotyledonous plants,
  insects, birds, bats or small mammals are
  employed to transfer pollen from plant to plant,
  usually in exchange for either nectar or pollen
  itself as a foodsource.
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  ??????????????????????,????????????????????????,??
  ???????????????????,????,?????????????????

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• ????(Leptonycteris curasoae)????????
• ??????????????????,???????????????????,???????????
  ??????? 1/3000??????????????,???????,?????????????
  

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• The interaction and connection between bees and
  flowers is a common example of mutualism. What
  is it that each species gets out of this
  interaction? Bees are able to gather nectar and
  pollen from flowers, giving them the nutrients
  necessary to produce, nourish and sustain
  offspring in order for the species to continue.
  Flowers are pollinated by the bees, increasing
  genetic variability within the plant species,
  allowing future generations to be strong enough
  to survive lifes inevitable uncertainties.

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Seed dispersal????

• Large seeds cannot be effectively wind-dispersed,
  and unless dispersal by water (as occurs in the
  coconut palm) occurs, such plants are dependent
  on animals for dispersal. Rodents, bats, birds
  and ants are all important seed dispersers.
• ?????????????,??????(??????),?????????????????????
  ???????????

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Defensive mutualisms???????

• Some mutualisms provide one partner with a
  defense against predators or competitors.
  Examples of such defensive mutualisms are found
  between some grasses and alkaloid-producing
  fungi, and between many plant species and ants.
• ??????????????????????????????????????????????????
  ????,?????????????

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Obligate mutualism??????

• Some mutualisms, such as lichens, are permanent
  pairings in which one or both partners cannot
  lead an independent life. Most symbiosis(??) are
  obligate, as are some nonsymbiotic mutualisms,
  such as those formed by fungus-farming ants.
• ???????,???,????????,?????????????????????????,???
  ???????????????,???-???????????

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Symbiosis??

• Mutualism may be symbiotic, in which the
  organisms live together in close physical
  association.???????????,???????????????????
• e.g.
• Lichens is fungus-algae symbiosis called
• Mycorrhizae is fungus-root symbiosis
• Nodule is nitrogen fixation bacteria-root
  symbiosis

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• ?? ??????,?????????,??????????
• ???N????????????????
• ?????????????????
• ????????????????????????????N?????????????
  ?,??????????????????,?????,?????,?????????,???????
  ??????????

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Symbiotic mutualists within animal tissues and
cells????????????????

• A number of animal species rely to some extent on
  mutualisms with mutualists which reside within
  their bodies. Ruminants (deer and cattle) possess
  a multi-chambered stomach in which bacterial and
  protozoan fermentation take place. In some
  termites, which feed on wood, the necessary
  breakdown enzymes are provided by bacterial
  mutualists. Intracellular bacterial symbionts
  which transform amino acids occur in a number of
  insect groups, including aphids and cockroaches.
• ?????????????????????????????????????(???)?????,??
  ????????????????????????????,?????????????????????
  ???????????,??????????????????

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Commensalism??(??)
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Commensalism??(??)

• Commensalism - one species benefits, the other is
  unaffected
• Spanish moss trees
• the moss gets a habitat
• the trees are unaffected
• growth is the same w/o the moss

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• ????(??)
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• ????????????(????)??????????

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Altruism

• Altruism occurs when an individual causes an
  increase in the fitness of another individual of
  the same species at a cost to its own survival or
  offspring production.
• ????????????????????????,??????????????????

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• An example is the sterile worker in a eusocial
  ant society, which sacrifices its opportunity of
  reproducing and instead supports its mothers
  reproduction.?????????????????,???????????,???????
  ??????????,???????????????
• This appears paradoxical, as it implies that the
  altruist is actively reducing its fitness,
  However, if the altruist is related to the
  beneficiary, this strategy may result in more of
  the altruists genes passing to the next
  generation.?????????????,??,?????????????????,????
  ?????????????????????

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Altruistic behavior(????)

• Cooperative altruism(??????????)working together
  and both get benefits
• Manipulative altruism(??????????)be unwilling to
  help others, but have to , just manipulated by
  others.

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Reciprocal altruism ??????????

• one individual provides another with help, and
  the second subsequently reciprocates or pays back
  the first. Simply you scratch my back, I will
  scratch yours.

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Evolution of helping behavior

• Group selection animal populations should
  restrict their population density and rate of
  reproduction rather than endanger their food
  supply through over-exploitation.

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• Coevolution and interspecific interactions.
• Coevolution refers to reciprocal evolutionary
  adaptations of two interacting species.
• When one species evolves, it exerts selective
  pressure on the other to evolve to continue the
  interaction.