Biodiversity and Extinction of Hawaiian Land Snails: How Many Are Left Now and What Must We Do To Conserve Them—A Reply to Solem (1990)

Abstract

Pacific islands, with their incredible biodiversity, are our finest natural laboratories for evolutionary, ecological and cultural studies. Nowhere, in relation to land area, does land snail diversity reach that of the Pacific islands, with more than 6,000 species, most of which are single island endemics. Unfortunately, land snails are the most imperiled group with the most recorded extinctions since the 1500s, and Pacific island snails make up the majority of those extinctions. In 1990, Dr. Alan Solem, a well renowned malacologist, with expertise in Pacific island land snails, posthumously published a plea to save the remaining Hawaiian land snails before they vanish forever. Now, more than 25 years later, we have finally begun to make inroads into answering the questions "How many Hawaiian land snails remain?" and "What will we need to save them?". Here we provide a belated reply to Solem (1990) and address these questions about Hawaiian land snails. We conclude by building on the actions suggested by Solem and that we feel are still needed to realize his hope of conserving Hawaii's remaining land snails specifically, but also our hope of conserving invertebrates more broadly.

Molecular phylogenetics and premating isolation in the punctoid land snails of Belau (Republic of Palau, Oceania)

“…There are still many more undescribed punctoid species across the Pacific (Solem, 1983), and within museum collections. There are as many as 300 endodontid species from the Hawaiian Islands alone, that have been awaiting formal taxonomic treatment for over 70 years (Solem, 1990; Yeung & Hayes, 2018). All but two species of Hawaiian Endodontidae are now extinct (Hayes et al., 2020).…”

Negative impacts of invasive predators used as biological control agents against the pest snail Lissachatina fulica: the snail Euglandina ‘rosea’ and the flatworm Platydemus manokwari

“…However, Solem (1990) estimated that 65-75% of this fauna was already extinct and Lydeard et al (2004) suggested that the figure could be as high as 90%. More detailed estimates based on surveys over the last decade, and including newly discovered cryptic species, indicate that the remaining fauna numbers approximately 290 species, with estimates of extinctions within families ranging from 30 to 97% excluding families with fewer than ten species (Régnier et al 2015b;Yeung and Hayes 2018;Hayes and Yeung unpublished). While widespread habitat modifications, shell collecting and other invasive species (e.g.…”

Measuring Biodiversity and Extinction—Present and Past

“…While the risks to a few iconic species are well known, the vast majority of named species have never been assessed according to IUCN criteria. Quantitative work on extinction must confront a historical assumption that, for example, small, cryptic land snails are widespread (Yeung and Hayes 2018) and less threatened than their more brightly-colored relatives. Larger, more brightly-colored and conspicuous species are better-studied and their biogeography and dispersal relatively more fully understood, yet better camouflaged species represent the majority proportion of species richness.…”

“…Larger, more brightly-colored and conspicuous species are better-studied and their biogeography and dispersal relatively more fully understood, yet better camouflaged species represent the majority proportion of species richness. These data gaps lead to under-estimation of human impacts, which in turn impact the public's perception of, and potential funding for, biodiversity discovery and analysis that are critical for developing conservation strategies (Yeung and Hayes 2018).…”