Proceedings of the 1St Joint Symposium on the Natural History and Geology of the Bahamas
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Proceedings of the 1st Joint Symposium on the Natural History and Geology of The Bahamas June 12-16, 2015 Conference Organizer: Thomas A. Rothfus Content Editors: Carol L. Landry Dan S. Kjar Production Editors: Lee J. Florea Carol L. Landry Gerace Research Centre San Salvador, Bahamas 2017 Copyright 2017, Gerace Research Centre All rights reserved. No part of this work may be reproduced or transmitted in any form by any means, electronic or mechanical, including photocopying, recording, or any data storage or retrieval system without the express written permission of the Gerace Research Centre. ISBN: 978-0-935909-40-1 Cover image - Patch reef near the wall off Grotto Beach (photo by Lee Florea). KEYNOTE ADDRESS Plant-animal interactions in the face of disturbance Suzanne Koptur Department of Biological Sciences, Florida International University, Miami, FL 1. Abstract 2. Introduction A multitude of interactions among plants and A number of plant/animal interactions are in- animals are shaped by the environment and volved in plant reproductive success, includ- influenced by disturbance at different levels. ing pollination, herbivory, and seed disper- Plant survival and reproduction are proximal- sal. Plant reproduction and survival may be ly influenced by edaphic conditions, which are influenced by disturbance at different levels. transformed dramatically through natural and Proximal effects are those affected by nearby anthropogenic phenomena including fire, hur- edaphic conditions, such as fire, hurricanes, ricanes, and environmental disasters, and ulti- and other natural disasters; ultimate effects are mately via water management, deforestation, those that shape the landscape, such as water and sea level rise. A number of plants are now management, deforestation/development, and listed as threatened or endangered due to hab- sea level rise. itat transformation and loss; many places once Similarities between the biota of southern full of native vegetation have been cleared for Florida and the Bahamas archipelago provide agriculture or urban development, and areas an interesting comparison and may allow us that were formerly seasonally inundated are to apply lessons learned from one place to the now dry. Plants in habitats that experience re- other. The flora of the Bahamas is overall more curring natural disturbances have been select- species-rich than that of southern Florida (Cor- ed for adaptations to changing conditions, and rell and Correll 1982), but individual islands display strategies of recovery such as resprout- each contain only part of the diversity. In the ing and/or reseeding after devastation by fire, Bahamas, pines occur only on the four larger or regrowing from damaged or downed stems islands (Grand Bahama, Abaco, New Provi- after hurricanes. Herbivory, pollination, and dence, and Andros) that have a freshwater lens, seed dispersal are three interactions affected providing the conditions suitable for the growth by disturbance: the degree to which plants are and survival of these glycophytic plants; on eaten by herbivores, how they are protected by these, and all the other islands, coastal vegeta- bodyguards, their flowers visited and pollen tion is present. Much of the Bahamas is south transported, and their fruits and seeds dispersed of Florida, with a much larger proportion of the by a variety of biotic agents, may increase, de- flora of tropical origins than that of the north- crease, or be changed in other ways. Disturbed ernmost islands (Correll and Correll 1982) and habitats are more likely to be invaded by ex- south Florida (Tomlinson 1980). otic pest species, which in turn may alter the interactions among plants and their native ani- 2.1. Ant/Plant mutualisms, plant defense, and mal partners. As global climate change affects fire the planet, sea level rise is a major concern for many ecosystems. Some species endemic to A substantial proportion of plants of Everglades Caribbean islands and coastal areas already re- upland habitats bear extrafloral nectaries (Kop- quire help in restoration of their habitats, and tur 1992a), glands outside of the flowers, gen- perhaps eventually will need assisted reloca- erally not involved with pollination, but rather tion for future survival. promoting visitation by ants and other benefi- 1st JOINT SYMPOSIUM ON THE NATURAL HISTORY AND GEOLOGY OF THE BAHAMAS 3 KOPTUR PLANT-ANIMAL INTERACTIONS cial insects that may result in plant protection diverse understory of Florida pine rocklands in facultative ant/plant mutualisms (Bentley has more than 250 herbaceous species (Sny- 1977; Koptur 1992b; Rico-Gray and Oliveira der et al. 1990), with a number of endemic 2007). Pine rocklands are fire-successional species. Some of these species are federally habitats that succeed to hardwood hammocks and state listed as endangered or threatened after 20 years or more without fire (Alexander due in large part to habitat loss; development 1967; Snyder et al. 1990). Ant activity at baits in southern Florida took place on the higher, is greater in pine rocklands than in hardwood dryer ground upon which pine rocklands and hammocks; baits are discovered more quick- hardwood hammocks historically occurred. In ly, and recruitment is greater (Koptur 1992a). the Bahamas, as in much of south Florida, the Cover of plants with extrafloral nectaries is original pine forests were logged as recently as higher in pine rocklands than in hardwood the mid-20th century; only in very remote plac- hammocks (ibid.), suggesting that ant/plant es (e.g. in Florida, Lostman’s Pines in the Big mutualisms are more likely to occur in pine Cypress National Preserve) are there pines of rocklands. Similar studies in the Bahamas, large diameter, an indication of their long lives, on the pine island of Andros, similarly found growing for years before the loggers harvested greater ant abundance in pineyards than in cop- the rest of their kind. pice (equivalent to hardwood hammocks), and We have been studying the effects of the the cover of plants with extrafloral nectaries disturbance of diminished habitat into small, also greater in pineyards (Koptur et al. 2010). separated patches (habitat fragmentation) on Comparing pineyards of different times since specialized vs. generalized pollination systems, fire, there was greater ant activity with less with the prediction that plant species especially time since fire; ants were abundant even in very vulnerable to negative effects of fragmentation recently burned sites (ibid.). are those with either specialized pollination In pine forests of both south Florida and and/or obligate outcrossing. To test this hy- the Bahamas there are many understory plants pothesis, we need to learn about the floral biol- adapted to fire; the majority of species resprout ogy and breeding system of study species, and from underground parts after their above- then collect evidence of pollination: visitor/ ground plant bodies have been killed by fire pollinator activity at flowers; presence of pol- (Maguire and Menges 2011), and some have len on visitors; and deposition of pollen on stig- contractile roots to protect meristems under- mas. The most telling data are those on fruit set ground during fires (Fisher 2008). Fire pro- from marked flowers, as those are evidence of motes flowering in many species of Florida’s successful pollination with compatible pollen. pyrogenic ecosystems (Abrahamson 1984a; Our methods are to collect comparative data Platt et al. 1988; Slapcinsky et al. 2010). Post- from multiple sites that are different sizes and fire, the understory is more open, a good time have different degrees of isolation from other for seed germination and seedling establish- pine rockland sites. For starters, we compared ment of understory plants (Abrahamson 1984b; four types of sites: 1) intact pine rockland (in Carrington 1999) and overstory pines as well Everglades National Park); 2) fragments great- (O’Brien et al. 2008). er than 10 ha in size (“large fragments”); 3) fragments 3 – 10 ha in size (“medium”); and 2.2. Habitat fragmentation and pollination 4) fragments < 3 ha. (“small”). In Keys pine rockland, we studied multiple urban edge and Pine rocklands are an imperiled, fire-depen- forest sites. dent habitat, unique to S. Florida and the Ba- Comparisons reveal fewer visitors to hamas, where they are called pineyards. The flowers for some plant species in fragments, 4 1st JOINT SYMPOSIUM ON THE NATURAL HISTORY AND GEOLOGY OF THE BAHAMAS KOPTUR PLANT-ANIMAL INTERACTIONS and fewer and some different animal taxa arenicola (Small) H.J.P.Winkler (Linaceae), within guilds (Koptur 2006). Some plant and Pentalinon luteum (L.) B.F.Hansen & species exhibit a shift in pollinators – in some Wunderlin (Apocynaceae)) also receive fewer species, native bees predominate in natural pollinator visits and their flowers set less areas, butterflies in fragments (Geiger 2002). fruit when they open in the weeks following Fruit set is only affected in species that are mosquito spray events (Harris 2016, and pollinator-dependent, such as Fabaceae species unpublished). Amorpha herbacea Walter var. crenulata Angadenia berteroi receive many more (Rydb.) Isely (Linares and Koptur 2010), visits from skipper butterflies than bees in Centrosema virginiana (L.) Benth. (Cardel habitat fragments, but it turns out that bees are and Koptur 2010), Chamaecrista lineata (Sw.) much better pollinators (Barrios et al. 2016a). Greene var. keyensis (Pennell) H.S.Irwin & These plants are also subject to much greater Barneby (Liu and Koptur 2003), and Senna damage from caterpillars of Syntomeida epilais mexicana (Jacq.) H.S.Irwin & Barneby var. Walker (the oleander moth) when there are chapmanii (Isely) H.S.Irwin & Barneby (Jones, ornamental plantings of oleander near the unpub. data), and most dramatically in those pine rockland fragment (Barrios Roque 2015). These caterpillars have a very large effect on that are self-incompatible, e.g., Byrsonima plant reproduction, consuming not only leaves lucida (Mill.) DC. (Malpighiaceae) (Downing but flowers and entire stems of plants upon and Liu 2013), Ipomoea microdactyla which their eggs are deposited. Griseb. (Convolvulaceae) (Geiger 2007), and Angadenia berteroi (A.DC.) Miers 2.3.