Adaptive Radiation & Convergent Evolution

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1 Adaptive Radiation & Convergent Evolution
Biology Evolution Dr. Theodore Garland, Jr. 1 Dec. 2015: Adaptive Radiation & Convergent Evolution This was a perfect length in 2011, but could some cleaning up and polishing. Etienne, R. S., and B. Haegeman A conceptual and statistical framework for adaptive radiations with a key role for diversity dependence. American Naturalist 180:E75-E89. Ted updated the parts about mammals and Hawaiian Honeycreepers in 2013. In 2015, this was a stand-alone lecture after deleting all of the QG. I finished the human sexual selection material before starting this. IN 2015 THIS WAS 30 MINUTES SHORT, EVEN WITH THE HUMAN SEXUAL SELECTION MATERIAL!!! I forgot to show the two sexual selection movies in 2015!!! Reading is pages and in Bergstrom, C. T., and L. A. Dugatkin Evolution. W.W. Norton and Company.

2 Adaptive Radiation

3 Adaptive Radiation = The diversification of members of a single phylogenetic lineage (clade) into a variety of different forms, under the action of natural selection.

4 Adaptive Radiation = Random genetic drift in combination with speciation (from whatever cause) will lead to a proliferation of species with varying morphologies, etc. That does not require diversifying natural selection, so it would not qualify as adaptive radiation.

5 Adaptive Radiation Four Common Causes: Environmental Change
Mass Extinctions (see next lecture) Invasion of Island Archipelagoes Key Innovations (a.k.a. General Adaptations)

6 Examples of Adaptive Radiation
Mammals Hawaiian Honeycreepers Bromeliads Anolis Lizards Horned Lizards (Phrynosoma) Darwin's (Galapagos) Finches African Rift Valley Cichlid Fishes

7 Reconstruction of Hadrocodium wui, an early Jurassic fossil (about 195 million years old)
Approx. 2 grams Paperclip is 32 mm Luo, Z.-X., A. W. Crompton, and A.L. Sun A new mammaliaform from the Early Jurassic and evolution of mammalian characteristics. Science 292: Mammals Cover photo of that issue. This was scanned in the default Auto Crop Photo mode, then cropped in Visioneer, then saved as a TIFF file, then inserted here.

8 Mammalian Phenotypic Diversity
(this phylogeny is not current) "The ~5400 described species of living mammals evolved to occupy diverse ecological niches and include arboreal, fossorial, volant, aquatic, and terrestrial forms - some of which exhibit 100 million-fold differences in body mass" (Meredith et al Science 334: ) MammalDiversity.jpg Page 140 from "Handbook of Physiology - Comparative Physiology"

9 Mammalian Phenotypic Diversity
(this phylogeny is not current) MammalDiversityonPhylogeny.jpg

10 A recent time-calibrated phylogeny for mammals
(several authors from UCR Department of Biology) "Molecular time trees and diversification analyses suggest important roles for the Cretaceous Terrestrial Revolution and Cretaceous-Paleogene (KPg) mass extinction in opening up ecospace that promoted interordinal and intraordinal diversification, respectively. By contrast, diversification analyses provide no support for the hypothesis concerning the delayed rise of present-day mammals during the Eocene Period." Robert W. Meredith, Jan E. Janecka, John Gatesy, Oliver A. Ryder, Colleen A. Fisher, Emma C. Teeling, Alisha Goodbla, Eduardo Eizirik, Taiz L. L. Simão, Tanja Stadler, Daniel L. Rabosky, Rodney L. Honeycutt, John J. Flynn, Colleen M. Ingram, Cynthia Steiner, Tiffani L. Williams, Terence J. Robinson, Angela Burk-Herrick, Michael Westerman, Nadia A. Ayoub, Mark S. Springer, William J. Murphy Impacts of the Cretaceous Terrestrial Revolution and KPg extinction on mammal diversification. Science 334: Robert W. Meredith, Jan E. Janecka, John Gatesy, Oliver A. Ryder, Colleen A. Fisher, Emma C. Teeling, Alisha Goodbla, Eduardo Eizirik, Taiz L. L. Simão, Tanja Stadler, Daniel L. Rabosky, Rodney L. Honeycutt, John J. Flynn, Colleen M. Ingram, Cynthia Steiner, Tiffani L. Williams, Terence J. Robinson, Angela Burk-Herrick, Michael Westerman, Nadia A. Ayoub, Mark S. Springer, William J. Murphy Impacts of the Cretaceous Terrestrial Revolution and KPg extinction on mammal diversification. Science 334:

11 They are not separate clades.
Hawaiian Honeycreepers - a diverse group of birds whose uniting features are a unique odor, proximally truncate tongue, and lack of lingual wings (Wagner, 1995). There are three kinds: Drepandini “red birds,” Psittirostrini “finch-billed birds,” Hemignathini “green birds” (Wagner, 1995). They are not separate clades. "FIGURE 100" from some book ...

12 Hawaiian Honeycreepers
"FIGURE 100" from some book ...

13 Hawaiian Honeycreepers: some older views of their phylogeny
"FIGURE 100" from some book ...

14 Hawaiian Honeycreepers
Figure 2. Bayesian Divergence Date Estimates for Hawaiian Honeycreepers from Whole Mitochondrial Genomes Based on Three Island Age Calibration Points [7] Mean ages are shown above each node, with horizontal bars across nodes representing 95% highest probability density intervals. Shaded vertical bars encompass the estimated subaerial to maximal shield-building dates for the recent Hawaiian Islands [1], where the gray bars indicate island ages used as calibrations, and asterisks (*) identify constrained nodes. Lowercase letters identify divergence of a new morphological lineage before formation of Oahu (a), during or after formation of Oahu (b), or before or during formation of Maui Nui (c). Distributions by island are listed to the right of each taxon where closed circles denote historic and/or extant (and sometimes fossil) distributions, and open circles represent fossil distributions with no known historic or extant populations. (1) The extant population occurs on Nihoa Island, but closely related extinct species mainly differing in size occurred on Kauai, Oahu, and Hawaii Islands. (2) The extant population occurs on Laysan Island, but closely related extinct species mainly differing in sizes occurred on Kauai and Hawaii Islands. (3) A closely related species or subspecies occurred on Laysan Island. Photographs are by Jack Jeffrey. Lerner et al Current Biology 21: Lerner, H.R.L., Meyer, M., James, H.F., Hofreiter, M., Fleischer, R.C Multilocus resolution of phylogeny and timescale in the extant adaptive radiation of Hawaiian Honeycreepers. Current Biology 21:

15 Hawaiian Honeycreepers
Our phylogenetic results are consistent either with a single evolutionary loss and subsequent gain of the finchlike morphology and feeding niche or with the persistence of a finch-like lineage with at least two gains of more thin-billed and warbler-like morphologies. In either case, the resolved molecular phylogeny reveals a more complex pattern of morphological evolution than would be expected based on classic papers about the radiation, which proposed phylogenetic patterns that minimized the morphological distance between related taxa. Lerner et al Current Biology 21: In other words, parallel or convergent evolution can confound phylogenetic analyses, as you already know! Lerner, H.R.L., Meyer, M., James, H.F., Hofreiter, M., Fleischer, R.C Multilocus resolution of phylogeny and timescale in the extant adaptive radiation of Hawaiian Honeycreepers. Current Biology 21:

16 Adaptive Radiation in Bromeliads
Bromeliads are members of a plant family known as Bromeliaceae (bro-meh-lee-AH-say-eye). It contains over 2,700 described species in approximately 56 genera. The most well known bromeliad is the pineapple. The family contains a wide range of plants including some very un-pineapple like members such as Spanish Moss (neither Spanish nor a moss). An epiphyte = grows on other plants. Takes nutrition and moisture from the atmosphere = "Air Plant." Other members resemble aloes or yuccas, while still others look like green, leafy grasses. Bromeliads are members of a plant family known as Bromeliaceae (bro-meh- lee-AH-say-eye). The family contains over 2700 described species in approximately 56 genera. The most well known bromeliad is the pineapple. The family contains a wide range of plants including some very un-pineapple like members such as Spanish Moss (which is neither Spanish nor a moss). Other members resemble aloes or yuccas while still others look like green, leafy grasses.

17 Spanish Moss (Tillandsia usneoides)

18 Adaptive Radiation in Bromeliads
Bromeliads are members of a plant family known as Bromeliaceae (bro-meh- lee-AH-say-eye). The family contains over 2700 described species in approximately 56 genera. The most well known bromeliad is the pineapple. The family contains a wide range of plants including some very un-pineapple like members such as Spanish Moss (which is neither Spanish nor a moss). Other members resemble aloes or yuccas while still others look like green, leafy grasses.

19 "With nearly 400 species, Anolis lizards represent the world's most species-rich amniote genus. This diversity is most striking on Caribbean islands, where anoles have undergone a remarkable adaptive radiation. On many islands, anoles are the most abundant and conspicious vertebrates, making them outstanding subjects for research."

20 Adaptive Radiation in Phrynosoma
13 species; 5 are live-bearing P. platyrhinos California P. cornutum Texas P. coronatum California P. douglassi Oregon

21 Family Phrynosomatidae
Squirt blood from eyes as a defense against canid predators Fringe-toed, Earless, and Zebra-tailed Lizards 10 species Ernest Hodges Horned Lizards 13 species Umascop30pct.jpg Others from Wendy Hodges 2004 ICVM talk Spiny & Tree Lizards 98 species Mid - Late Oligocene 30 MYA

22 Horns are a Synapomorphy of Phrynosoma

23 and show substantial variation within the clade:

24 Parietal Horns Phrynosoma douglasii Phrynosoma mcallii

25 Temporal Horns Phrynosoma douglasii Phrynosoma mcallii

26 But why have some species mostly lost their horns?
Why do the 13 species of Phrynosoma show so much variation in horn size and shape? As discussed in a previous lecture, we know that current natural selection is favoring large horns in at least one species, at present: Young, K. V., E. D. Brodie Jr., E. D. Brodie III How the horned lizard got its horns. Science 304:65. But why have some species mostly lost their horns? Have they found other ways to avoid predation? Are large horns costly? (remember beetle example) Why did horns originate in the first place? See also Doug Emlen selection experiment and comparative studies of beetles, but note that these horns are mostly thought to be under sexual selection …

27 Adaptive Radiation in Darwin’s Finches
13 or 14 species

28 Adaptive Radiation in Darwin’s Finches

29 Herrel, A. , J. Podos, S. K. Huber, and A. P. Hendry. 2005
Herrel, A., J. Podos, S. K. Huber, and A. P. Hendry Evolution of bite force in Darwin’s finches: a key role for head width. Journal of Evolutionary Biology 18: Herrel, A., J. Podos, S. K. Huber, and A. P. Hendry. 2005a. Evolution of bite force in Darwin’s finches: a key role for head width. Journal of Evolutionary Biology 18: [9 species, n = 2-137, means and SD, independent contrasts with DOS PDAP]

30 Another Classic Adaptive Radiation
Lakes of the African Rift Valley hold hundreds of species of closely related cichlid fishes. See Harvey and Pagel (1991, pp ).

31 An interesting fact: cichlid females are mouth brooders
Barlow, 2000 Spawning of Mouth Brooder Cichlids The spawning routine starts with fin flaring and lip locking between the male and female. This is their way of flirting and finding the right mate. The male cichlid, if he has found the female to his liking, will sneak off and dig a spawning pit in the gravel at the bottom of the tank. The male will start flaring his fins and swimming closely to the female in order to excite and entice the female. Then the male and female will start swimming in circles with the male taking the lead over to the spawning pit. As they are swimming around in circles above the spawning pit, the female drops her eggs in the pit. Then she immediately goes back and picks up the eggs in her mouth. The male has egg spots on his anal fin that makes the female think there are eggs she has missed. She approaches the male tries to pick the egg spots off the anal fin. At this moment, the male releases sperm into the female’s mouth, thus fertilizing the eggs. The female holds the fertilized eggs in her mouth until the gestational period is over. Depending on the species, gestation periods can range from 18 to 25 days. You can tell the female is pregnant because she will develop a bruise on the throat due to the babies inside her mouth growing bigger. She will also stop eating until the eggs are hatched. This requires you to pay close attention to the female fish in your tank. Care of Cichlid Mother and Babies Do not leave the mother in with the babies for any longer than 4 days. She will start to eat the babies, thinking this is her food source. Don’t worry about the babies eating; they are very capable of eating fish food as soon as they are let out of the mother’s mouth. In order to be humane, feed the female well before putting her back into the community tank. Females can starve to death if they have successive pregnancies. Having an additional small tank for the mother’s recuperation is a good idea. Do not put the babies into a community tank until they are at least 3 to 4 inches long. Depending on the number of babies, you may need to put them in a larger tank as they continue to grow. Fryer and Iles, 1972

32 African Rift Valley Cichlids
These closely related species differ in shape, color, and feeding habits. Evolution was very rapid: within the last few million years.

33 One explanation is ecological
The fish are bottom nesters. Even though lake water is very clear, nesting at the bottom results in a very short line-of-sight. Barlow, 2000

34 One explanation is ecological
M. zebrata Females use male color for choosing mates (i.e., sexual selection occurs). Local “dialects” can develop quickly.

35 A second explanation has to do with skull structure

36 Cichlids have a normal set of teeth
See Harvey and Pagel (1991, pp ).

37 Plus a “bonus” set of pharyngeal teeth
This may constitute a “key innovation” Barlow, 2000

38 Redundancy is Beneficial
…allows one set of teeth to maintain regular function … while the other can adapt to perform new duties. Barlow, 2000

39 Key Innovations: Also known as "general adaptations."
A derived characteristic that allows a new way of life. May lead to adaptive radiation. Examples: 1. flight 2. amniotic (cleidoic) egg 3. ability to digest cellulose 4. endothermy

40 But this is hard to test in a rigorous fashion, in part because many putative key innovations are unique evolutionary events. Suppose that a given clade has a putative “key innovation” and is more diverse in terms of numbers of species and/or amount of “morphospace” occupied, as compared with its sister clade. This evidence is not strong, but rather is like what we have when comparing only two species! Could easily just be a coincidence …

41 You could call this an artificial "adaptive" radiation …

42 Marsupials are another good example of adaptive radiation, and also …

43 Convergent Evolution

44 Convergent Evolution =
Evolutionary changes in two or more unrelated organisms that result in the independent development of similar adaptations to similar environmental conditions. (Ancestors were more different than the descendants.)

45 Species a and b are convergent.

46 Convergent similarity (homoplasy) is not uncommon
New World cactus Family Cactacea Old World “cactus” Family Euforbicea

47 Convergent similarity (homoplasy) is not uncommon
Thylacine (marsupial wolf) Wolf (placental)

48 Marsupials show multiple convergences with placental mammals
"Mammals exhibit striking examples of ecomorphological convergence that has led to contentious debates in modern systematics" (Meredith et al Science 334: )

49 The same cichlid phenotypes occur in different lakes and taxa

50 Australian Moloch horridus (only 1 species) is convergent with the 13 Phrynosoma
Have a “false head” that makes it hard for snakes to swallow P. platyrhinos California P. cornutum Texas Moloch1.jpg shrunk to “Low” quality in Dell Image Expert And Moloch horns are not underlain by bone. P. coronatum California P. douglassi Oregon

51 The convergence is only skin deep …
To cite this page: Dr. Eric Pianka, 2003, "Moloch horridus" (On-line), Digital Morphology. Accessed February 23, 2005 at Commonly known as thorny devils, the Australian agamid lizard Moloch horridus is protected from predation by numerous sharp spines on its head, body, legs and tail. When threatened, thorny devils tuck their head between their forelegs, leaving the prominent spiny "false head" on the back of their necks in the position of their real head, making them virtually impossible to swallow. They also utilize camouflage to escape detection. Thorny devils are ant specialists, eating virtually nothing else. Phrynosoma cornutum (left) vs. Moloch horridus (right) North American horned lizards (genus Phrynosoma; see P. cornutum and P. taurus) are also ant eaters and are distantly related ecological equivalents. No other lizards are as spiny. Moloch and Phrynosoma are often cited as a classic example of convergent evolution. One can argue that camouflage and spines constitute part of an adaptive suite that facilitates specialization on ants, as follows. Because ants are eusocial insects, they constitute a clumped food supply which fosters specialization. However, because ants contain chitin and noxious chemicals such as formic acid, they are not overly nutritious and must be consumed in large quantities. This requires a large stomach. These lizards sit and wait along an ant trail, picking up ants with their tongues. The tank-like body form and spiny protection of thorny devils and horned lizards enables this ecology. Thorny devils possess more spines than horned lizards, and they are at least as sharp. Using high-resolution X-ray computed tomography we made 3-D digital reconstructions of this thorny devil and of two species of horned lizards (Phrynosoma cornutum and P. taurus). Entire preserved specimens were scanned, such that they could be rendered with flesh, then the flesh made transparent and their skeletons rendered. Spines on the heads of horned lizards (right, top) have prominent bony cores on the skull, so we fully expected the thorny devil's skull to show similar bony spines. However, we were surprised that the thorny devil skull has only two small bosses on its parietal and a small ring of calcified blobs around the base of the prominent vertical horns above their eyes (right, bottom). Most of their spines, including the false head, are entirely boneless. Moloch is nevertheless stunningly spiny via dermal armor alone, demonstrating that convergent evolution need not exploit the same mechanisms to achieve a given anatomical endpoint. P. cornutum (top) vs. M. horridus (bottom); semi-transparent flesh in blue, bone in red Another example of "multiple solutions"

52 Dawkins, R. 1996. Climbing mount improbable. W. W. Norton & Co
Dawkins, R Climbing mount improbable. W. W. Norton & Co., New York. xii pp. [pages discuss convergence; Fig.1.9 shows hedgehog, shrew hedgehog, hedgehog tenrec, and long-tailed tenrec. Fig 1.10 shows bottlenose dolphin, Ichthyosaurus, blue marlin, and Galapagos penguin]

53 Extra Slides Follow Etienne, R. S., and B. Haegeman A conceptual and statistical framework for adaptive radiations with a key role for diversity dependence. American Naturalist 180:E75-E89.

54 An Updated Phylogeny for Eutherian (placental) Mammals
Murphy, W. J., E. Eizirik, S. J. O'Brien, O. Madsen, M. Scally, C. J. Douady, E. Teeling, O. A. Ryder, M. J. Stanhope, W. W. de Jong, and M. S. Springer Resolution of the early placental mammal radiation using Bayesian phylogenetics. Science 294: Murphy, W. J., E. Eizirik, S. J. O'Brien, O. Madsen, M. Scally, C. J. Douady, E. Teeling, O. A. Ryder, M. J. Stanhope, W. W. de Jong, and M. S. Springer Resolution of the early placental mammal radiation using Bayesian phylogenetics. Science 294: