The palatable plants investigated in this study gained significant protection from herbivores by associating with abundant competitors that were less susceptible to herbivory. When herbivores were excluded, palatable species associated with unpalatable ones grew at only 14%-19% of the rate of palatable plants separated from unpalatable ones. When herbivores were present, however, palatable species appeared to depend completely on unpalatable competitors to provide microsites of reduced herbivory to prevent grazers from causing local extinction of the preferred species. For the species studied here, the cost of being associated with a larger, unpalatable competitor was much less than the cost of increased consumption in the absence of that competitor. Under these conditions, one competitor can have a strong positive effect on another. Associational defenses can provide an unappreciated mechanism for maintaining species richness within communities that are dominated by one or a few major species. In this co...

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Associational Plant Defenses and the Maintenance of Species Diversity: Turning Competitors Into Accomplices

This paper provides an analysis of the distribution patterns of marine biodiversity and summarizes the major activities of the Census of Marine Life program in the Caribbean region. The coastal Caribbean region is a large marine ecosystem (LME) characterized by coral reefs, mangroves, and seagrasses, but including other environments, such as sandy beaches and rocky shores. These tropical ecosystems incorporate a high diversity of associated flora and fauna, and the nations that border the Caribbean collectively encompass a major global marine biodiversity hot spot. We analyze the state of knowledge of marine biodiversity based on the geographic distribution of georeferenced species records and regional taxonomic lists. A total of 12,046 marine species are reported in this paper for the Caribbean region. These include representatives from 31 animal phyla, two plant phyla, one group of Chromista, and three groups of Protoctista. Sampling effort has been greatest in shallow, nearshore waters, where there is relatively good coverage of species records; offshore and deep environments have been less studied. Additionally, we found that the currently accepted classification of marine ecoregions of the Caribbean did not apply for the benthic distributions of five relatively well known taxonomic groups. Coastal species richness tends to concentrate along the Antillean arc (Cuba to the southernmost Antilles) and the northern coast of South America (Venezuela – Colombia), while no pattern can be observed in the deep sea with the available data. Several factors make it impossible to determine the extent to which these distribution patterns accurately reflect the true situation for marine biodiversity in general: (1) highly localized concentrations of collecting effort and a lack of collecting in many areas and ecosystems, (2) high variability among collecting methods, (3) limited taxonomic expertise for many groups, and (4) differing levels of activity in the study of different taxa.

/pdf/marine-biodiversity-in-the-caribbean-regional-estimates-and-3uevi7d6l0.pdf

Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns

Experimentally determined ranges of thermal tolerance and requirements for completion of the life history of some 60 seaweed species from the North Atlantic Ocean were compared with annual temperature regimes at their geographic boundaries. In all but a few species, thermal responses accounted for the location of boundaries. Distribution was restricted by: (a) lethal effects of high or low temperatures preventing survival of the hardiest life history stage (often microthalli), (b) temperature requirements for completion of the life history operating on any one process (i.e. [sexual] reproduction, formation of macrothalli or blades), (c) temperature requirements for the increase of population size (through growth or the formation of asexual propagules). Optimum growth/reproduction temperatures or lethal limits of the non-hardiest stage (often macrothalli) were irrelevant in explaining distribution. In some species, ecotypic differentiation in thermal responses over the distribution range influenced the location of geographic boundaries, but in many other species no such ecotypic differences were evident. Specific daylength requirements affected the location of boundaries only when interacting with temperature. The following types of thermal responses could be recognised, resulting in characteristic distribution patterns: (A) Species endemic to the (warm) temperate eastern Atlantic had narrow survival ranges (between ca 5 and ca 25°C) preventing occurrence in NE America. In species with isomorphic life histories without very specific temperature requirements for reproduction, northern and southern boundaries in Eur/Africa are set by lethal limits. Species with heteromorphic life histories often required high and/or low temperatures to induce reproduction in one or both life history phases which further restricted distribution. (B) Species endemic to the tropical western Atlantic also had narrow survival ranges (between ca 10 and ca 35°C). Northern boundaries are set by low, lethal winter temperatures. Thermal properties would potentially allow occurrence in the (sub) tropical eastern Atlantic, but the ocean must have formed a barrier to dispersal. No experimental evidence is so far available for tropical species with an amphi-Atlantic distribution. (C) Tropical to temperate species endemic to the western Atlantic had broad survival ranges (<0 to ca 35°C). Northern boundaries are set by low summer temperatures preventing (growth and) reproduction. Thermal properties would permit occurrence in the (sub)tropical eastern Atlantic, but along potential “stepping stones” for dispersal in the northern Atlantic (Greenland, Iceland, NW Europe) summer temperatures would be too low for growth. (D) In most amphi-Atlantic (tropical-) temperate species, northern boundaries are set by low summer temperatures preventing reproduction or the increase of population size. On European shores, species generally extended into regions with slightly lower summer temperatures than in America, probably because milder winters allow survival of a larger part of the population. (E) Amphi-Atlantic (Arctic-) temperate species survived at subzero temperatures. In species with isomorphic life histories not specifically requiring low temperatures for reproduction, southern boundaries are set by lethally high summer temperatures on both sides of the Atlantic. None of the species survived temperatures over 30°C which prevents tropical occurrence. Species with these thermal responses are characterized by distribution patterns in which southern boundaries in Eur/Africa lie further south than those in eastern N America because of cooler summers. In most species with heteromorphic life histories (or crustose and erect growth forms), low temperatures were required for formation of the macrothalli (either directly or through the induction of sexual reproduction). These species have composite southern boundaries in the north Atlantic Ocean. On American coasts, boundaries are set by lethally high summer temperatures, on European coasts by winter temperatures too high for the induction of macrothalli. Species with this type of thermal responses are characterized by distribution patterns in which the boundaries in Eur/Africa lie further north than those in eastern N America because of warmer winters.

https://link.springer.com/content/pdf/10.1007%2FBF02366043.pdf

Relative importance of temperature and other factors in determining geographic boundaries of seaweeds: Experimental and phenological evidence

A critical evaluation of the phylogeny and evolution of the plants classified as bacteria, algae, and fungi has been made. The evolution of chemical characters (porphyrins, carotenoids, carbohydrates, and lipids and sterols), micromorphological characters (cell wall, hereditary apparatus, flagellar apparatus, photosynthetic apparatus, mitochondria, and Golgi apparatus), and functional characters (metabolism of hygrogen, nitrogen, sulfur, and carbon, including respiration, photosynthetic energy transformation, and photosynthetic carbon fixation) are discussed. Phylogenetic interrelations among thallophytes are evaluated on the basis of each of these characters. The final section of the review discusses the phylogeny of organisms in the divisions and classes of the thallophytes as suggested by chemical, micromorphological, functional, and life cycle criteria.

A consideration of the evolutionary and taxonomic significance of some biochemical, micromorphology, and physiological characters in the thallophytes.

: A detailed description is given of the community structure and ecosystem processes of the mangrove forests of south Florida. Information covered ranges from details of mangrove distribution, primary production, and diseases to aspects of reproduction, biomass partitioning, and adaptations to stress. Mangrove ecosystems are considered in terms of zonation, succession, litter fall and decomposition, carbon export, and energy flow. Most of the components of mangrove communities are cataloged and discussed; these include microorganisms, plants other than mangroves, invertebrates, fishes, reptiles, amphibians, birds, and mammals. Finally, two sections summarize the value of mangrove ecosystems to man and present ways to manage this type of habitat.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a323074.pdf

The Ecology of the Mangroves of South Florida: A Community Profile

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1961.6.1.0099

A. J. Bernatowicz

Papers

Marine Algae of the Eastern Tropical and Subtropical Coasts of the Americas