Evolutionary genomics of endangered Hawaiian tree snails (Achatinellinae: Achatinellidae) for conservation of adaptive capacity

BACKGROUND

In the last five years,nearly all populations of Hawaiian tree snails in the subfamily Achatinellinae (Achatinellidae) have declined to undetectable levels. Nearly 100 species have existed historically, but habitat loss, overcollection, and predation by invasive species have decimated populations. As such, this system offers theopportunity to integrate efforts to conserve evolutionary potential into conservation planning for a rapidly declining subfamily.

A. LILA

METHODS In this study we used genome-wide, restriction- site associated DNA sequencing (RADseq), along with mitochondrial genome reconstruction, to resolve evolutionary relationships to inform conservation efforts. N. CUMINGI

RESULTS

Island Both the mitochondrial and * AMU1 1. AMU2 * AMU3 genome-wide SNP approaches AMU4 * AMU 5 AMU6 * supported polyphyly in the AMU20 * AMU21 * AMU22 genera and Perdicella, AMU7 * AMU8 * AMU10 and results suggest that dwarfism AMU11 AMU9 AMU12 may have evolved multiple times * * AMU13 AMU19 AMU14 O’ahu * across the species complex. AMU15 * AMU16 * AMU17 * AMU18 * ALI1 MAXIMUM LIKELIHOOD TREE OF THE ‘MINIMALLY ALI2 FILTERED’ GENOME-WIDE SNPS DATASET * ADE1 * ASO1 * ASO4 * ASO2 * * ASO3 Genus ASO5 ASO6 AUN1 Achatinella AFUS1 AFUL1 * * AFUL2 Partulina * AAP1 ALI3 ABU1 Perdicella * PER1 Maui PMI1 Moloka’i * PSE1 * PVA1 PTE1 * * PHE1 PHE2 * ESU * PPR1 PPR2 Moloka’i ESU A * PPR3 ESU B PRE2 ESU C ESU D * * PRE3 ESU E PRE4 ESU F PRE1 * * PPE2 PTER1 Maui *=95-100 ML * PPE1 NCU1 * * PPH1 Hawai’i 0.1 * crassula

Tornitellides irregularis

2. Populations of are likely in the process of undergoing speciation, with cryptic divergence among populations at levels comparable to, or deeper than, accepted species within the family, based on both mitochondrial and genome- wide SNP phylogenetic and coalescent analyses.

3. Conservation of evolutionary potential is critical across this subfamily. Given the divergence within species among populations that are geographically proximate (sometimes within one kilometer), our results indicate that with each population that becomes extirpated by invasive predators, a significant amount of within- species diversity is lost.

MAP SHOWING LOCATIONS OF 22 SPECIES IN THE SUBFAMILY ACHATINELLINAE ACROSS THE HAWAIIAN ARCHIPELAGO

4. Due to the genetic structuring over dramatic environmental gradients across multiple mountain ranges and islands, this study system appears ideal for examining the ability to predict adaptation to future conditions.

IMPLICATIONS FOR CONSERVATION

Given the extirpation rate of populations due to invasive predators, few (if any) are likely to remain outside of exclosures within the next decade. Since conservation of biodiversity must include conservation of genetic diversity, construction of exclosures in climate-suitable areas is urgently needed, along with captive propagation efforts.

This is an open access graphic distributed under the terms of the Creative Commons Attribution License. Evolutionary genomics of endangered Hawaiian tree snails (Achatinellinae: Achatinellidae) for conservation Image credits: of adaptive capacity JaroslavImage credits: Červený PeerJ 9:e10993 DOI: 10.7717/peerj.10993 David Sischo http://peerj.com/articles/10993