Reproductive biology and responses to threats and protection measures of the total population of a Critically Endangered Galápagos plant,Linum cratericola(Linaceae)

Abstract

We describe a reproductive and population dynamic study of the total population of a Critically Endangered plant over 10 years, during which part of the population was protected from the main threat, feral ungulates. Linum cratericola (Linaceae) was first discovered in 1966 at two sites on Floreana Island, Galápagos. It has since disappeared from one site and survives in three groups of plants at the other, where it has been threatened with extinction by introduced ungulates and invasive plants. Population size, and growth rate and mortality of individual plants, have been monitored since 1997. The population appears highly responsive to changes in threat levels: the three plant groups increased rapidly following protection by fencing and ungulate control, but temporarily declined when feral goat pressure increased and during dry periods. Natural factors that may contribute to population limitation include dry years, grazing by native snails and competition from native vascular plants and cryptogams. Linum cratericola has a single flowering period per year and produces abundant seed with 28% germination after scarification, but with no obvious adaptations for long-distance dispersal. Potential pollinators included the butterfly Leptotes parrhasioides, the hoverfly Toxomerus crockeri and the carpenter bee Xylocopa darwinii, all endemic to Galápagos. The continued survival of L. cratericola in the wild depends on effective protection from introduced herbivores and invasive plants.

Comparative Genetic Structure and Demographic History in Endemic Galápagos Weevils

“…In the case of native widespread species, if the 2 species were to compete it does not follow that the native species would necessarily be immediately displaced (Leger and Espeland 2010), even though introduced species have been shown to pose significant competitive threats to native populations (Stokes et al 2009). For endemic species with restricted populations or those such as G. conwayensis that effectively function as isolated populations due to the extremely unlikely transport across islands, intervention, protection from introduced and invasive counterparts, and monitoring have been proposed as important components for the island native's continued survival (Cole et al 2005;Garrett et al 2007;Simbana and Tye 2009).…”

Impacts by feral goats on critically endangered Crepidiastrum grandicollum (Compositae) endemic to the Ogasawara Islands

“…Oceanic islands are biodiversity hotspots with highly endemic ecosystems, which exhibit various island syndromes such as loss of dispersal ability, woodiness in herbaceous species and an increase in dioecious plants (Carlquist, 1974;Whittaker & Fernandez-Palacios, 2007), but insular ecosystems are vulnerable to invasive alien species (Courchamp, Chapuis, & Pascal, 2003;Walsh et al, 2012;Whittaker & Fernandez-Palacios, 2007). In particular, alien herbivores have a considerable impact on insular vegetation (Fernández-Lugo, Arévalo, de Nascimento, Mata, & Bermejo, 2013;Hamann, 1975) and populations of endemic endangered plants (Atkinson, 1989;Caujapé-Castells et al, 2010;Simbaña & Tye, 2009). Insular plants have often lost the ability to defend against herbivory by alien animals as a result of long-term isolation (Atkinson, 1989;Bowen & Van Buren, 1997;Carlquist, 1974;Courchamp et al, 2003).…”

Joseph Dalton Hooker (1817-1911) - a great Linnean

“…Darwin and Hooker exchanged many letters from the 1840s to the 1880s (see the Darwin Correspondence Project: http://www.darwinproject.ac.uk/), and, in addition to islands (e.g. Carlquist, 2009; Porter, Murrell & Parker, 2009; Simbaña & Tye, 2009), they shared many botanical interests including carnivorous plants (e.g. Chase et al ., 2009) and orchids (e.g.…”

“…Publications in recent issues of the Botanical Journal of the Linnean Society contain many references to the publications of Hooker. These include articles relating to the angiosperm families Apiaceae (Degtjareva et al ., 2009), Bromeliaceae (De Faria, Wendt & Brown, 2010), Combretaceae (Maurin et al ., 2010), Commelinaceae (Cabezas et al ., 2009), Fabaceae (Cusma‐Velari & Feoli‐Chiapella, 2009; Lackey, 2009), Gunneraceae (González & Bello, 2009), Hydrangeaceae (Liu & Zhu, 2011), Lamiaceae (Bramley, 2009; Wang & Hong, 2011), Liliaceae (Wang et al ., 2009), Linaceae (Simbaña & Tye, 2009; McDill & Simpson, 2011), Melastomataceae (Reginato, Michelangeli & Goldenberg, 2010), Nepenthaceae (Chase et al ., 2009), Orchidaceae (Micheneau et al ., 2009; Pupulin, 2010; Adams, 2011), Poaceae (Sun et al ., 2010), Ranunculaceae (Ehrendorfer et al ., 2009), Rosaceae (Chin et al ., 2010) and Sarraceniaceae (Chase et al ., 2009), gymnosperms (Gnetales; Rydin, Khodabandeh & Endress, 2010) and bryophytes (Wilbraham, 2010). The number and wide taxonomic coverage of these articles clearly demonstrate the ongoing significance of his scientific legacy.…”