CHAPTER 6 Factors Affecting Distribution and Abundance 4ABIOTIC

CHAPTER 6 Factors Affecting Distribution and Abundance : 4)ABIOTIC FACTORS 1

Learning Outcome • Define abiotic factors • Acquire knowledge on the influence of non living factors towards living organism • Understand the application of abiotic factors in nature 2

What is abiotic factors? • Abiotic factors = the non-living factors • which affect the ability of living organisms to survive in an environment. These can include both physical and chemical factors. • Some examples of physical abiotic factors are soil, weather, and the availability of consumable water. Natural disasters can also be considered abiotic. • Examples of chemical factors include the amount of sunlight and the p. H level of the soil. 3

How Organisms Tolerate Temperature & Moisture? 1. Each organism has a range of temperature. 2. Organisms also acclimate physiologically. 3. Temperature & moisture limit distribution. 4. Organisms respond differently to the same environmental variables during different phases of their life cycles (eg. udang putih/kertas – Penaeus merguiensis; Siakap, sea bass – Lates calcarifer) 4

Penaeus merguiensis, Udang putih 5

• How temp or moisture can limits distribution of organism? i. determine the phase of the life cycle that is most sensitive (juvenile white prawn is sensitive to high salinity) i. determine the physiological tolerance range of the life cycle phase (mature white prawn can reproduce and responsive at high salinity/marine) 6

Example 1 - Passerine birds tolerate with temperature • The range limits of endotherms (warm blooded) correlates with climatic variables. • The distribution of passerine birds in North America correlates with minimum temperature. • The northern temperature limit of the phoebe (passerine bird) is -4 o. C. – linked with the energetic demand associated with temperature. – lower temperature requires higher metabolic rates to maintain body temperature and also there is a limit to feeding rates. 7

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Example 2 - Red kangaroo tolerate with moisture • The distributional boundary of the red kangaroo (Megaleia rufa) coincides with the 400 mm rainfall contour and do not spread outside the rainfall contour – the red kangaroo feed generally on arid zone grasses that are restricted to low rainfall areas. 9

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Example 3 - Plants tolerate with moisture • Plants resistance to drought is achieved by: i. Improvement of water uptake by roots – deeper roots ii. Storage of water – cacti iii. Prevention during drought season: - reduce water loss via stomata or - reduce cuticular respiration, thick cuticles in cacti - reduction of leaf surface area – small leaves, - peeling of leaves during drought (xerophytes) - orientation of leaves - succulent/moist leaves and stem in Bryophyllum and Euphorbia 11

Interaction Between Temperature & Moisture • Drought can restrict plant distribution. Two types of drought: 1) soil drought ii) frost drought/winter drought 12

Example 1 • Loblolly pine (Pinus taeda) • Northern limit set by winter – winter drought – rate of water uptake in loblolly pine decreases rapidly in winter – water not available in liquid form 13

Northern limit- winter temperature and rainfall Western limit - winter temperature and rainfall 14

Example 2 – Intertidal Zone • 2 species of barnacles dominate the British coast: – a) Chthamalus stellatus – b) Balanus balanoides 15 Balanus balanoides Chthamalus stellatus

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• a) Chthamalus stellatus - southern species – dominant in the upper intertidal zone and high tolerance to long exposure to air • Its upper limit is set by desiccation. • Its lower limit set by competition for space with Balanus balanoides. • C. stellatus can survive in the Balanus zone if the latter is removed. 17

• b) Balanus balanoides - (northern species) has (1) faster growth as compared to C. stellatus and so force out the latter from the middle intertidal zone. • Its upper limit is determined by temperature and dessication – it (2) has lower tolerance for higher temp and dessication, that’s why it cannot occupy C. stellatus space. • Its lower limit is set by competition of space with algae and predation by a gastropod – Thais lapillus 18

Adaptation to Temperature & Moisture : Ecotype • There are certain physiological tolerances built into all individuals of a particular species. • Local adaptation can occur and that genetic and physiological uniformity cannot be assumed throughout the range of the species (e. g. as shown by Aurelia aurita) Aurelia aurita 19

• Species can extend their distribution by local adaptations to limiting environmental factors. • Turreson (1922) demonstrated the concept of ecotype – genetic varieties within a single sp (Example : Aurelia aurita) • He also show variations associated with climate and soil in a plant species, Plantago maritima. 20

Example : Ecotype • Turreson (1925) collect plants (Plantago maritima) from a variety of areas and grow them in field or laboratory plots at one site. • He worked with 2 varieties • tall & robust ones grow along the marshes along the coast • dwarf plant on exposed sea cliffs on Island. 21

Experimental design: • He planted the seeds side by side Result: • the plants from the coast (tall and robust) were significantly taller than those from the cliffs • this showed ecotypes, populations adapted to local conditions 22

As a conclusion…. • Plants of the same species growing in diverse environments can differ in morphology and physiology in 3 ways: 1. all differences are phenotypic – seeds transplanted from one situation to the other they will respond exactly as the resident 2. all differences are genotypic – seeds are transplanted, mature forms will retain as in original habitat. E. g. Plantago maritima 3. some combination of phenotypic and genotypic determination produces an intermediate result – in nature this is most usually observed. E. g. P. glandulosa 23

Light as factor that brings about Distribution & Abundance Importance: 1. Cue for timing of day/night (plants) essential for photosynthesis 2. Cue for timing seasonal rhythms (animals) – spawning/breeding season Light as a cue • some organisms use light as a cue for activity cycles – response to day length changes. Day and night length are vary and not constant. • Behavior and physiological reaction towards variation in duration of day/night – photoperiodism 24

Example 1 • Plant response differently towards day light. • The rate of photosynthesis can be measured by the rate of CO 2 uptake. • sunlight- energy absorption by plant-restrict photosynthesis at certain level, restrict the glucose production 25

Light as Factor that Brings about Distribution & Abundance 2. Light as a cue for animals: - Many organisms use day length as a behavioral cue. - Birds can be brought to breeding condition in mid winter by increasing day length artificially. 26

Example 2 • Breeding seasons have evolved to occupy part of the year in which offspring have the greatest chances of survival • Birds in temperate zones use spring time - increasing/longer day length in spring - to begin nesting cycle at a point when adequate food resources will be available for their young in nest and as fledglings. • light as a cue- bird can predict the perfect time for breeding 27

Why light is important for plant? • Plant species become adapted to live in a certain kind of habitat • Prevent them from occupying other habitats - Eg Hemlock – shade tolerant – seedlings can survive in forest understorey under very low light levels – grow slowly/low metabolic rates. - One consequence – they die easily in drought – roots do not grow quickly to penetrate deep into the soil to look for water. 28

• Adaptations to live in one ecological habitat make it difficult or impossible to live in a different habitat. 29

Light Adaptation – Example 1 • Seaweeds show a variety of response to light adaptation. • 2 types of seaweeds occur (1) monolayered, flat, wide thalli (2) highly dissected (multilayered), narrow thalli, • Morphological adaptation: – 1) Monolayered seaweeds would be advantage at low light levels in deeper waters – 2) Multilayered seaweed would be advantage at high light intensity in shallow water 30

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Example 2 - Rate of photosynthesis • • 1. 2. 3. The rate of photosynthesis under given light conditions can affect whether the plant can survive in different environments One reason why photosynthetic rate varies among plants is that there are 3 different biochemical pathways by which photosynthesis reactions can occur: C 3 (most plants) – CO 2 converted to 3 -phosphoglyceric acid (3 carbon molecule, C 3); C 4 plants (sugar cane) – CO 2 fixed as malic and aspartic acid (4 carbons molecule, C 4) CAM (Crassulean Acid Metabolism)- cacti and any desert plant 32

Differences between C 3 and C 4 leaves • Leaf anatomy of C 3 and C 4 plants differ. • Chlorophyll in C 3 plants are found throughout the leaf • Chlorophyll in C 4 plants it is concentrated in Krantz Anatomy and they have a high concentration of mitochondria • C 4 plants do not reach saturation light levels even in bright sunlight and produce more photosynthetic per unit area of leaf than do C 3 plants 33

Anatomical differences between C 3 and C 4 leaves. C 3 LEAF Photosynthesis occurs within the mesophyll cells in C 3 plants, which form a dense layer on the upper surface of the leaf and a spongy layer on the lower surface. Bundle-sheath cells surrounding the veins are not photosynthetic. C 4 LEAF Dense layers of mesophyll cells surround the bundle-sheath cells of C 4 plants. Both the bundle-sheath cells and the rings of mesophyll cells are photosynthetic. 34

• The C 4 anatomy is more efficient – C 4 plants are at an advantage when photosynthesis is: 1. occurs under high light intensity and high temp - C 4 grasses are at a selective advantage in warmer areas with high solar radiation 2. limited by CO 2 concentration and water is in short supply • Type C 4 grasses, sedges and dicotyledons are all more common in tropical area, North America than in temperate or polar regions (Fig. 7. 15) • On mountains in Hawaii, which have small seasonal changes in temp, C 3 grasses predominate at high elevations (low temperature) and C 4 at low elevations (high temperature) 35

Water Chemistry • Studies on freshwater Rotifers – p. H and bicarbonate ions seem to be most important 36

Salinity Tolerance Adaptation High salinity Low salinity Salt Marsh Plant Distribution in Relation to Salinity Tolerance A salt marsh is a type of marsh that is a transitional intertidal between land salty or brackish water 37