Plant adaptations to different growth conditions

Transcription

1 Plant adaptations to different growth conditions

2 Oh the places you ll grow: Plant adaptations to different growth conditions - where does it fit? Core Standard: Observe, describe, and ask questions about structures of organisms that affect their growth and survival Observe and describe how offspring are very much, but not exactly, like their parents or one another Observe, compare, and record the physical characteristics of live plants or animals from widely different environments, and describe how each is adapted to its environment Design an investigation to explore how organisms meet some of their needs by responding to information from the environment Describe a way that a given plant or animal might adapt to changes as the result of human impact on the environment.

3 Process Standards The Nature of Science Students gain scientific knowledge by observing the natural and constructed world, performing and evaluating investigations and communicating their findings. These principles should guide student work and be integrated into the curriculum along with the content standards on a daily basis. Make predictions and formulate testable questions Design a fair test. Plan and carry out investigations as a class, in small groups or independently, often over a period of several class lessons. Perform investigations using appropriate tools and technology that will extend the senses. Use measurement skills and apply appropriate units when collecting data. estimate predictions with multiple trials. Keep accurate records in a notebook during investigations and communicate findings to others using graphs, charts, maps and models through oral and written reports. Identify simple patterns in data and propose explanations to account for the patterns. Compare the results of an investigation with the prediction.

4 Overview What all plants have in common... The major climate zones and plant adaptations to them A hands on exercise with insect-eating plants

5 What all plants have in common All plants require nutrients (See Hopkin s cafe, mighty good!) C, H, O, P, K, N, S, Ca, Fe, Mg Water, air, soil sunlight Then why are there so many different plant species? Shouldn t after time only one most competitive species remain?

6 What plants differ in most plants grow in a much wider range of conditions (e.g. in botanical gardens) than we find them in nature, but this only works if we shield them from competition in nature plants differ in exactly what kinds of conditions they grow best in relative to their competitors And: plants differ in what other things they do that give different species unique advantages

7 Three major climate zones and the challenges (and opportunities) they provide We will focus on... temperate zone deserts rain forest deserts temperate zone

8 But first some quick background: We will focus on... temperate zone deserts rain forest deserts temperate zone 4 questions for you: (1) Why do we have different climates as we move from equator to pole? The sun's rays hit the equator at a direct angle between 23 N and 23 S latitude. Radiation is most intense here. As one moves north or south the rays arrive at an increasingly smaller angle to the surface and therefore the less intense the radiation.

9 But first some quick background: 4 questions for you: We will focus on... temperate zone deserts rain forest deserts (2) Why do we have the same climates on the northern and southern half of our planet? The intensity of the sun s radiation decays similarly whether one moves north or south of the equator temperate zone

10 But first some quick background: 4 questions for you: We will focus on... temperate zone deserts rain forest (3) Why is Earth a bit like a rotisserie chicken? Ehm, I mean what gives us seasons? deserts temperate zone

11 Another way of looking at seasons Equinox Solstice

12 Last question (4) Why do climate zones often still differ even though they are on the same latitude? Climate is not just affected by the intensity of radiation and seasonality but also by... prevailing winds and whether they bring moist warm air or cold dry air proximity to nearest ocean the resulting precipitation or lack thereof barriers to clouds such as mountain ranges...

13 OK, we are all set now: Three major climate zones and the challenges (and opportunities) they provide We will focus on... temperate zone deserts rain forest deserts temperate zone

14 I. Rainforests and the tropical climate zone What characterizes tropical climate and growth conditions?

15 I. Rainforests and the tropical climate zone What characterizes tropical climate and growth conditions? warm; modest fluctuations between day and night high humidity and much rain, during most/all parts of the year (annual precipitation ~ 260 cm. (100 in.) in wet rain forests (but can go even higher) modest seasonality little to no variation in day length throughout the year water is generally abundant, in fact sometimes there is way too much sun light is reasonably abundant in higher strata but not near ground level tropical soil is poor in nutrients...

16 II. Deserts and the arid climate zone What characterizes desert climate and growth conditions?

17 II. Deserts and the arid climate zone What characterizes desert climate and growth conditions? substantial daily temperature fluctuations, cold (but not freezing) to very hot extremely dry most of the year, low humidity, (annual precipitation: 0.25 cm (0.1 in) in Sahara; 7-30cm (3-12 in) in Sonoran desert). if rain than concentrated during brief parts of the year, then pronounced seasonality with a brief rainy season and a long dry season as a consequence sun light is over-abundant but water is (extremely) rare even in rainy deserts, rainy seasons may skip a year or 2 or 3...

18 III. Temperate climate zone What characterizes temperate climate and growth conditions?

19 III. Temperate climate zone What characterizes temperate climate? significant daily temperature fluctuations substantial seasonal temperature fluctuations depending on region, e.g. 24C/43F for Great Basin region, 7C/12F for Mediterranean, 31C/56F for deciduous forests water availability fluctuates during the year but good at least during part of it annual precipitation <10 cm (4 in) in the driest regions to 50 cm (20 in) in the moister steppes and the mediterranean to 81 cm (32 in) in deciduous forests. but overall: winter = cold and dry season soil quality is poor to extremely good

20 Climate adaptation in real plants Please examine the plants that are before you Which climate might these plants be adapted to? What features might allow them to cope particularly well with the climatic conditions in their respective habitat? Please work as a group at each table and be prepared to present your results in a little while to the rest of us

21 I. List of plant adaptations to tropical climates large dark-green leaves (= lots of chlorophyll) to absorb sun light, especially in understory with lots of shade leaf arrangement maximizes light capture slick waxy cuticle to allow rain to run off shallow roots (no need to go deep for nitrogen or water) and buttress or stilt roots (to help with stability) epiphytic life style (orchids, bromeliads, ferns, cacti etc) allows to be near sun light; soil not that great anyway, aerial roots instead many climbing plants (lianas, strangler figs, rattan, etc) continuous growth (no year-rings in trees); trees can reach enormous hights...

22 II. List of plant adaptations to desert climates Sun avoidance and tolerance; small leaves or no leaves at all to minimize water loss photosynthesis instead often in trunk leaves frequently modied to spines which aid in defense but also can reflect excess light accordion trunk to reduce sun exposure special CO2 capture mechanism (C4/CAM) to minimize water loss while absorbing CO2 highly reflective cuticle to reflect excess light dense hair to generate isolating boundary layer extremely seasonal growth and reproduction long lived, must be able to skip years if seasons don t allow succulence; storing of water in specialized tissues (fleshy leaves, trunks, underground etc) also extensive and deep root system

23 III. List of plant adaptations to temperate climates annual life cycle deciduousness when perennial if not deciduous then leafs are needles protected by thick cuticle to survive winter thick bark to protect against cold winters

24 The best way in Bloomington to survey up close the diversity of plant adaptations to different climates is... The Jordan Hall Greenhouse Public Hours: M-F 7:30 am - 4:00 pm S&S 9:00 am - 3:00 pm Group tours available by appointment: Phone: (812) biogreen@indiana.edu or through yours truly

25 Now on to a very special group of plants Carnivorous plants!

26 Carnivorous plants some background Carnivory has evolved independently several times in diverse groups of plants Carnivorous plants photosynthesize like regular plants, but they also catch insects (and sometimes larger animals) If insects are withheld carnivorous plants can still grow but do less well

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28 YOUR TASK: The plants before you are all carnivorous Given what you know about insects and plants, please investigate the following questions 1) Why do they catch insects? 2) How do they catch insects? 3) Once caught, what do they do with them? Please form hypotheses that address these questions, and brainstorm about potential experimental tests. We will ask you to share your progress and insight periodically, and also provide you with some additional information along the way, which may or may not further complicate your analysis

29 Additional information I Many carnivorous plants lack the ability to digest insects! (i.e. they can t make the right enzymes)

30 Additional information II The pitchers of many carnivorous plants are home to specialized insects that do not get eaten by the plant

31 Additional information III If these insects are removed the plant does poorly, just like when you remove the plant s insect prey

32 1)Why do they catch insects and (3) once caught, what do they do with them? Carnivorous plants generally grow in nitrogen poor environments, such as bogs. They supplement their nitrogen input through the digestion of insect prey. This digestion may be enabled by the plant s own enzymes (venus fly trap) or the digestive abilities of bacteria and insects that coinhabit pitchers. 2) How do they catch insects? Many cool adaptations: pitcher plants often have nectaries on edge of pitcher (attracts prey), slippery edge (facilitates capture), downward facing hair (impedes escape), and false window above pitcher (makes insects fly toward light but then bounce against lid). sundews have attractive but sticky droplets bladderworts have touch-sensitive underwater bladders that open and suck in prey venus fly trap has nectar glands inside trap and touch sensitive closing mechanism

33 But: Doesn t all sort of non-food crap fall into the trap (like what?)? One last task! Please investigate closely the venus fly traps before you and form one or more hypothesis as to if and how the trap might be able to distinguish between different objects, such as a water droplet, debris, or live insect. Then brainstorm about possible experiments you could do to test your hypothesis. Then present your hypothesis and experiment and see if we can do it! Q: Can the trap tell the difference, and if so how does it know when to close and when to stay open?

34 Possible approaches Q1: Can the trap distinguish between food and non-food? H1: yes it can H2: No it cannot Test: drop small stick vs live fly into trap; trap will close only for fly, H1 is supported Q2: How does it distinguish? H1: must be edible H2: must be warm H3: must move... Test: select appropriate contrasts Q3: How is motion sensed? H1: prey bangs against wall H2: prey moves sensory hairs (once/multiple times?) H3: trap hears its prey scream Test: immitate appropriate behavior with forceps

35 Thank you!