Chapter 21.1 Biodiversity and Conservation. Biodiversity ~2million different species have been...

Chapter 21.1

Biodiversity and Conservation

Biodiversity

• ~2million different species have been identified and named– Biologists theorize that there may be hundreds of

millions of species left to identify– Species are grouped into 5 (sometimes 6) large

categories called kingdoms

Kingdom Prokaryota

• Many biologists split this kingdom into two: the Archaea and the Bacteria (they look similar but have different biochemistry properties)

• Characteristic features of prokaryotes– Cells with no nucleus– DNA exists as circular chromosome– Smaller circles of DNA called plasmids are often present– No membrane bound organelles– Only 70S ribosomes present– Cell wall consisting of peptidoglycans– Usually exist as single cells or small groups of cells

Kingdom Protoctista

• Made up of very diverse range of organisms that don’t really fit into other kingdoms

• (Kind of like the random bin of organisms)

Kingdom protoctista

• The characteristic features of protoctists:– Eukaryotic– Mostly single celled or exists as groups of similar

cells– Some have animal-like cells (no cell wall) and are

sometimes known as protozoa– Others have plant-like cells (with cellulose cell

walls and chloroplasts) and are sometimes known as algae

Kingdom Fungi

• Characteristic features of fungi are:– Eukaryotic– Do not have chlorophyll and do not photosynthesize-

they feed heterotrophically– Simple body form: may be unicellular or made up of long

threads called hyphae (with or without cross walls) large fungi such as mushroom also have a compact mass of cells as part of their life cycle

– Reproduce by spores– Cells have cell walls made of chitin (not cellulose)– Never have cilia or flagella

Kingdom Plantae

• Characteristics of plants are:– Multicellular eukaryotes with cells that are

differentiated to form tissues– Some cells have chloroplasts and photosynthesize– Cell walls are always present and made of

cellulose– Cells may occasionally have flagella, for example

male gametes in mosses

Kingdom Animalia

• Multicellular eukaryotes with cells that are differentiated to form tissues

• Do not have chloroplasts and feed heterotrophically

• Do not have cell walls• Cells sometimes have cilia or flagella

Maintaining biodiversity

• Biodiversity can be defined as the degree of variation of life forms in an ecosystem

• Usually taken to include diversity at 3 levels:1. The number & complexity of communities in the

ecosystem2. The number of diff. species in the ecosystem3. The genetic diversity of all the species in the

ecosystem


• Biodiversity is essential to maintain ecological stability

• The measure and extent of biodiversity can be regarded as a measure of the ‘health’ of an ecosystem– High biodiversity= healthy– Low biodiversity- sick


• As our human population expands and use more and more resources from diff. environments, biodiversity is being threatened

• Species are being lost @ alarming rate• Conservation involves attempting to slow

down, stop, or reverse the loss of biodiversity


• The loss of biodiversity also presents an ethical dilemma: We share our planet with a huge range of other organisms and we have no right to make them extinct


• Biodiversity within an ecosystem helps to maintain stability

• All of the organisms in an ecosystem interact in many different ways, and if one species disappears, it can have ripple effects throughout the entire community


• There are also direct benefits to human to maintain biodiversity– Around 7000 drugs that are prescribed the doctors

are derived from plants– Almost 70% of these plants grow in tropical rain

forests– There are doubtless many more possible

pharmaceuticals that we do not know about, but if we allow tropical rain forests to disappear, then we are losing potentially life saving drugs


• The drugs vincristine and vinblastine (used to treat cancers of white blood cells) are derived from the Madagascan periwinkle.

• Madagascan periwinkle is endangered in the wild due to slash and burn agriculture– Fortunately, THE plant is being cultivated in many

different countries


• Also, we could use wild plant or animal species to introduce new and useful alleles into our crop plants and farmed animals– Ex: species of rice Oryza longistaminata , which

grows wild in Mali, is not suitable for cultivation as a crop plants b/c of its low yield and poor taste. However, it is resistance to a large number of strains of bacterial blight. It has successfully been interbred with cultivated rice to give varieties of rice that are resistant to the disease

Do Now 2.25

• 1.) List the main differences between a prokaryotic cell and a eukaryotic cell. Which kingdoms are prokaryotic? Eukaryotic?

• 2.) Which kingdoms contain heterotrophic organisms?

Endangered species

• The International Union for Conservation of Nature (IUCN) annually publishes a Red List of threatened species

• 2011 list contained 16,119 species• Species in the Red List are all under threat of

extinction- disappearing forever from the Earth.

Endangered species

• Mass extinction events in which millions of species become extinct at once have occurred several time throughout Earth’s history, but all have been due to natural events caused by sudden and huge changes in the environment– Ex: asteroid colliding with planet

Endangered species

• Currently facing likelihood of another mass extinction event due to habitat loss– Ex: draining wetlands, deforestation, slash and

burn agriculture, and pollution of air and water– Also, some species are becoming extinct due to

over harvesting (hunting, fishing, etc…)

Endangered species

• High profile animals on the Red List: pandas, tigers rhinos– Ex: World Wide Fund for Nature (WWF) based

2011 Holiday advertisement around its Adopt-A-Tiger campaign

• Less inclusion of invertebrates, protists

Endangered species

• 2011 estimates suggest that the global population of all tiger species is about 5000.

• In India, the pressure on the remaining tiger population is intense due to a rapidly expanding population

• In China, tiger products are valued as a cure to a variety of illness, so organized poaching is common

SAQ 21.5

• Suggest why the Red List contains more vertebrates than invertebrates.

SAQ 21.5

• Suggest why the Red List contains more vertebrates than invertebrates.

• One possibility is that people are much more aware of vertebrates than invertebrates, so we know more about them. They are larger and more visible than invertebrates. Many people find them more interesting than invertebrates.

Endangered species

• 2011: western black rhino of Africa declared extinct by IUCN– Northern white rhino declared “probably extinct

in the wild”– It is thought that the last Javan rhino in Vietnam

was killed by poachers in 2010– Only the African southern white rhino is

flourishing, up from only 100 individuals in start of 20th century

Endangered species

• Rhino extinctions, despite years of conservation efforts, continue because of:– A lack of political support for conservation– An increasingly high demand for rhino horn– Internationally organized criminal groups targeting

rhinos

Endangered species

• In order to compile its Red List, IUCN must complete a new census of each species

• Population numbers are estimated using visual sightings, paw marks, bite marks, droppings, and DNA analysis of droppings

Rescuing endangered species

• Scimitar-horned oryx lives in semi-deserts in northern Africa

• Has always been hunted for its meat and skin, but hunting grew exponentially starting in 1950s

• Listed as endangered in 1960s and 70s• A few oryx were caught and transported to

zoos throughout the world


• Captive breeding program began with captured oryx

• Care was taken to maintain as much genetic diversity in captive population as possible, so oryx from several different zoos were mated using artificial insemination


• While captive breeding was taking place, attempts were being made to provide safe habitats for the oryx, so they could be returned to the wild

• Large reserved set up in Tunisia• 1985: 10 oryx released to reserve• 2000: population has grown to over 120


• While the oryx program has been a success, some animals simple refuse to breed in captivity

• Often, it is not possible to create suitable habitats for them, so they cannot be returned to the wild– Ex: captive breeding program for Pandas. Since

1963, 300 pandas have been returned to the wild but no panda has been successfully returned to the wild

SAQ 21.6

• Suggest why some animals cannot be bred in captivity

SAQ 21.6

• Suggest why some animals cannot be bred in captivity

• They may need particular factors in their environment before their reproductive systems become able to produce sperm or eggs – for example, to have plenty of space, or to have many others of their species around them. These factors affect their physiology and their behaviour. Courtship may be difficult in the conditions in which they live. They may need particular changes in day length or in food supply to trigger hormonal changes associated with reproduction.


• When animals in captivity refuse to breed, various techniques as well as artificial insemination can be used:– Eggs can be collected from fertile females and

fertilized by in-vitro fertilization– In some species, another female of a closely

related species can act as a surrogate– It is sometime possible to split early embryos,

essentially cloning them


• In many species, sperm, eggs, and embryos can be stored frozen for later use

• Such banks of frozen gametes and embryos from endangered species are called “frozen zoos”

Protection of endangered species

• Zoos and botanic garden help lead to public awareness and support for endangered animals and plants

• Millennium Seed Bank: bank’s ambition is to collected and store seeds from at least 25% of the world’s plants so that if they become extinct in the wild, they can still be grown from seeds


• 2007: beginning of Svalbard Global Seed Vault. – Storage conditions ideal for long term

preservation of seeds– Opened only during winter months– By Jan 2008 vault held over 500,000 different crop

varieties• To maintain viability of seeds, every 5 years seeds are

germinated and new seeds are harvested from resulting plants


• To maintain genetic diversity, multiple seeds of the same species are stored – Every time a stored seed is germinated, it is cross

pollinated to maintain genetic diversity


• In order to safely store seeds, they must be dehydrated to contain only about 5% water

• Some seeds, like rubber, coconut palm, and coffee cannot be dried and frozen– These seeds are referred to as recalcitrant seeds– Only ways to keep the genetic diversity of these

species are to collect seeds and grow successive generations or to keep them as tissue culture


• Coconut palm are particularly difficult seeds to bank

• The seed (coconut) is very large and embryo is too large to freeze successfully

• Collectors remove the embryos from the seeds, culture them in sterile tubes, and eventually plant them

SAQ 21.7

• It has been suggested that seed banks put selection pressure on the seeds that are different from those that plants would experience in the wild.– How might these selection pressures differ?– How might this affect the chances of success in

returning the plants to the wild?

SAQ 21.7

• a Selection pressures in the natural habitat might include the ability of the adult plants to survive grazing, wide variations in rainfall or competition with other species. In the seed bank, none of these selection pressures would apply. In the seed bank, the greatest selection pressure will become the ability of the seeds to survive the conditions in which they are stored for a long period of time.

• b It is possible that the plants that grow from the seeds that have been saved will not have characteristics that will allow them to survive the selection pressures they will encounter in their natural habitat. This could reduce the chances of success in returning them to the wild.


• Most countries now set aside areas where wildlife and the environment can live protected in the wild where human activities are limited– Ex: conservation areas may be set up where there

are strict limits on building, grazing farm animals, hunting, or other activities that would adversely affect native species


• National parks are areas of land that are controlled by the government and are often protected by legislation

• There are heavy restrictions on human activities in these parks, and tourism brings in money to pay for their maintenance


• World’s first national park: Yellowstone National Park, set up in 1872

• Last remaining nearly intact ecosystem of the northern temperate climatic zone

• Serves as both a recreation and a conservation zone

Chapter 21.1 Biodiversity and Conservation. Biodiversity ~2million different species have been...

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