Animal Behaviour and Plant Responses. Year 13 Biology

Environmental Cycles The astronomical cycles –The motions of the Earth, moon and sun result in complex and interdependent cycles. –These create environmental changes that range from short term to long term.

Biological Rhythms Environmental cues such as daylength, timing and the height of tides, and phase of the moon are often used by plants and animals to establish and maintain a pattern of activity. They synchronize important events in the life cycle of an organism.

Biological Rhythms Biological rhythms in direct response to environmental stimuli are said to be exogenous – the rhythm is controlled by an environmental stimulus that is external to the organism Those rhythms that continue in the absence of external cues are said to be endogenous

The Biological Clock Biological clock – an internal timing system which continues without external time clues, and controls the timing of activities of plants and animals. Uses of biological clocks –Control of the daily rhythms of the body e.g. sleep, pulse, metabolic rate, sex drive –Reproductive timing –Preparing for migration by eating a lot of food –Preparing for winter by storing a lot of food –Navigating by the sun or the stars.

Some Biological Rhythms Circadian – daily activity period, approximately 24 hours (circa=about, dies=day) Circatidal – tidal activity period, approximately 12.4 hours Circasemilunar – spring/neap tidal period, approximately 14.7 days (semilunar=half moon) Circalunar – monthly activity period, 29 days (circa=about, lunar=moon) Circannual – yearly activity period, approximately 360 days (circa=about, annual=year)

Daily Cycles in Animals (circadian rhythms) Animals are active at different times of the day: –Diurnal – active during the day, inactive at night –Nocturnal – active at night, inactive during the day –Crepuscular – active at dawn and dusk –Arrhythmic – no regular pattern

Other Important Terms Free running period – when the biological clock is running without any cues for the environment, so is ‘running free’ Entrainment – the resetting of the biological clock on a regular basis, forcing it to take up the period of the environment. This is done with a Zeitgeber. Zeitgeber – (‘time giver’ – the German word is the most commonly used) – the environmental agent that resets the biological clock. This could be light, temperature etc.

Plant Rhythms Plants are capable of responding to environmental variables in a variety of ways. Some activities follow daily rhythms, while others are seasonal.

Photoperiodism in Plants Photoperiodism is the response to the relative length of daylight and darkness. Photoperiodic activities are controlled by a pigment called phytochrome. It acts as a signal for some biological clocks in plants and is also involved in other light initiated responses such as germination, shoot growth and chlorophyll synthesis.

The flowering of Plants A photoperiodic response of plants depends on the critical night length Plants can be divided into 3 types: –Short-day plants –Long-day plants –Day-neutral plants

The flowering of plants Short-day plants –Require a short day and long night –Will flower if the photoperiod is less than a certain critical length –See page 69 workbook –Long-day plants –Require a long day and short night –Will flower if the photoperiod is greater than a certain critical length

The flowering of plants Day-neutral plants –Flowering is unaffected by the amount of daylight per day.

The Phytochrome System Photoperiod of plants controlled by pigment phytochrome There are two forms of this pigment –P665 (Pr) – inactive form that absorbs red light –P725 (Pfr) – active form that absorbs far-red light

The Phytochrome System So how does it all work? –During the day P665 absorbs red light (present during the day) and as a result is quickly converted to the active form, P725. –This P725 then accumulates. –During the night P725 absorbs far-red light (present during the night) and slowly converts back to the inactive form, P665.

The Phytochrome System What is the link between this system and flowering? –If the day is long enough P725 accumulates and long-day plants flower –If the night is long enough P665 accumulates and short-day plants flower (it is thought that this may be due to the low concentration of P725 rather than high concentrations of P665) –See page 68 workbook

Plant Pigments Bailey p:28 Review Bailey Chapter 2. Try the questions at the end.

Plant Responses to the Biotic Environment Plant-plant relationships Plant-fungi relationships Plant-animal relationships Plant defences (aggressive) Co-operative relationships

Plant-plant relationships Relationships between plants are more complex than you might think. Examples –Allelopathy – this is when a plant may secrete a toxic substance from their roots or leaves that inhibits plants growing near them. E.g. Chaparral bush, black walnut –Seed dispersal mechanisms – ensures spread of offspring over a wide area

Plant-plant relationships –Growing larger leaves to capture available light when it is reduced –Plants arranging in layers (stratification) in response to differing environmental conditions (will have adaptations enabling them to survive in certain layers) –Epiphytes – grow on other trees to gain access to better conditions –Lianas – plant climbs up trees –These are just some examples –

Plant-fungi relationships Many plants will form relationships with Fungi –Mycorrhizal fungi form mutualistic relations with many plant roots. The fungi help the plant roots absorb water and minerals and in return get organic molecules (nutrients) made by the plant by photosynthesis –Obligate mutualistic relationships – lichen (made up of algae and fungi) that are obliged to live together. Fungi absorbs water and nutrients and keeps the algae wet and the algae carries out photosynthesis and provides sugars and food for the fungus.

Plant-animal relationships Herbivores eat plants by –Grazing –Browsing –Suck sap –Feed on nectar, pollen, fruit and seeds –Chew roots –Eat gum

Plant defences Plants must have strategies to defend themselves against herbivory. –Examples Thorns Divarication Chemicals Low growing point Seed masting Hiding etc

Co-operation in plants Co-operative interactions between plants and other plants, and plant and animals can include –Pollination – animal pollinators (insects/birds) are attracted by rewards or advertisements –Guarding plants by animals –Animals gaining protection from thorns –Eating fruits and seeds pass through digestive track and are dispersed Self check page 208 C.B

Animal Responses to the Biotic Environment Intraspecific responses – aggressive and co-operative Interspecific responses – aggressive and co-operative

Intraspecific aggressive responses Agonistic behaviour –Is aggressive –Towards members of the same species –Involves threats or fighting –Determines which competitor gains access to resources. –Especially strong between members of the same sex e.g. males fighting over females.

Intraspecific aggressive responses Territories –Are established areas for feeding, mating or rearing young, that are defended. –Held by aggressive behaviours –Usually consist of a lair or nest in the centre of the territory, surrounded by a large home range that animals cover regularly in search of food and mates. –Only the territory is defended

Intraspecific aggressive responses Advantages of territoriality –Ensures space for each animal –Reduces disease –Harder for predators to find animals if they are spread out –Reduces fighting –Ensures there is enough food for everyone –Safe breeding sights that are defended –Best genes are handed on to offspring

Intraspecific aggressive responses Disadvantages of territoriality –Males without territories fail to breed as not seen as attractive –Losers must spread out to find food rather than fight

Intraspecific aggressive responses Marking and defending –Singing –Mark with urine –Using scent glands –Using signals –Calling See page 234 C.B. for examples

Intraspecific aggressive responses Hierarchies –when every animal is either above or below another (linear hierarchy). –There are no equals –Forms “Pecking Orders” (see pg 234 C.B.) –Usually established competitively –“top dog” will usually make decisions for the group –Maintained by posture and display

Intraspecific co-operative behaviour Includes –Group formation –Courtship and pair-bond formation –Parental care

Group Formation When animals join together to co- operatively undertake tasks –E.g. Hunting, defence, protection etc

Advantages of forming groups Team work while hunting leads to increased success rate. Less predation as can have members of the group on “look out” Older members protect young or weak individuals Large numbers can cause confusion for predators Breeding sites are located within a boundary that is protected by members of a group

Disadvantages of group formation Competition is increased Disease can spread faster Parasites (e.g. fleas) spread faster Increases conflict between members

Courtship/pair-bond formation Requires co-operation, suppression of aggressive behaviours and communication. Usually females make the choice who they mate with, but both partners need to make sure; –They are the same species –Both fertile –Both fully prepared to mate.

Courtship Males usually will compete for the attention of females by; –Competing with other males by fighting or ritualised combat –Compete indirectly by attracting females by displays and adornments E.g. antlers in deer, brightly coloured feathers in peacocks, singing and dancing of many bird species, producing pheromones.

Pair-bond relationship A stable relationship between animals of the opposite sex that ensures co-operative behaviour on mating and rearing of the young –E.g. turns, albatross

Parental Care Survival depends on successfully breeding adequate numbers of offspring. Can be achieved by two possible strategies –R-strategy – produce large numbers of unprepared offspring with a low chance of survival –K-strategy – produce few, well prepared offspring which have a high chance of survival

Parental Care Degree of parental care depends on the species –E.g. eggs buried and then abandoned (many fish species), nest constructed and defended, offspring themselves defended –Often those species that have a high degree of parental care will teach their offspring how to find food, where to find water, how to make a home etc.

Reproductive Strategies Monogamy – each mating with only one member of the opposite sex (often for life) Polygyny – males mate with many females thus fathering many offspring Polygamy – dominant males mates with a harem of females Polyandry – females mate with more than one male Polygynadry (promiscuity) – both male and female mate with more than one member of the opposite sex.

F35A20FF2&v=YmVZ8zXJO48&fea ture=player_detailpagehttp:// F35A20FF2&v=YmVZ8zXJO48&fea ture=player_detailpage Hammer Orchid and Wasp - SqxQ&list=PL0CC0E52BC7BCC6D1&feat ure=player_detailpagehttp:// - SqxQ&list=PL0CC0E52BC7BCC6D1&feat ure=player_detailpage

Death with Lily 8xgcPY&list=PL0CC0E52BC7BCC6D1&fe ature=player_detailpage

Stench Flower 5_oig&list=PL0CC0E52BC7BCC6D1&feat ure=player_detailpage

Water Plant Reproduction C0E52BC7BCC6D1&v=7- 7QqpmaOSY&feature=player_detailpage

Lock and Key TLDQLQ&list=PL0CC0E52BC7BCC6D1&f eature=player_detailpage

Pollination, Plants and Insects ayer_detailpage&v=FiwkJui2mh0&list=PL0 CC0E52BC7BCC6D1