Conservation biology of three threatened Limonium species endemic to Zakynthos Island (Ionian Islands, Greece)


ANNA -T H A LA SS IN I VA LLI 1 ,CHARIK L E I A P AP AIO ANNOU2 ,ELENI L IVE R I 3 VASIL EIOS PAP ASO T IR OPOULO S 4 and PANAY IO TIS TRIGAS * 1


Abstract Knowledge of the life history traits, reproductive biology and demography of rare species is fundamental for their conservation, yet plant population monitoring is uncommon. The restricted ranges of the Limonium species endemic to the Mediterranean area, combined with the vulnerability of their specialized littoral habitats, indicate the need for appropriate conservation measures. We evaluate the conservation status and estimate the fu- ture extinction risk of three Limonium species endemic to Zakynthos Island in the Ionian Islands, Greece (Limonium korakonisicum, Limonium phitosianum and Limonium za- cynthium) using 5 years of monitoring data. We compile information on their geographical distribution, population dynamics, reproductive biology and genetic diversity. Population sizes and survival rates of seedlings exhibited marked annual fluctuations, although fecundity and rela- tive reproductive success remained high throughout the monitoring period. We observed a dominance of mature individuals in all three species, indicating their increased tolerance to salinity. Three subpopulations each of L. phi- tosianum and L. zacynthium were genotyped using five microsatellite loci. The observed number of alleles and the low gene flow value potentially indicate reduced gen- etic diversity, inbreeding, and limited gene flow within and among subpopulations of both species. Based on the IUCN categories and criteria, we assess L. korakonisi- cum as Critically Endangered, L. phitosianum as Near Threatened and L. zacynthium as Endangered. Population viability analyses predict that, among the three species, L. zacynthium will face the highest risk of extinction within the next 50 years. Knowledge of the biology of these species provides data essential for identifying critical factors for their survival and for proposing targeted con- servation measures.


*Corresponding author, trigas@aua.gr 1Laboratory of Systematic Botany, Department of Crop Science, Agricultural


University of Athens, Athens, Greece 2Laboratory of Genetics, Department of Biology, University of Patras, Patras,


Greece 3Laboratory of Botany, Department of Biology, University of Patras, Patras,


Greece 4Laboratory of Plant Breeding and Biometry, Department of Crop Science, Agricultural University of Athens, Athens, Greece


Received 27 August 2023. Revision requested 11 November 2023. Accepted 18 January 2024. First published online 30 October 2024.


Keywords IUCN criteria, Limonium, littoral species, Mediterranean plants, microsatellites, monitoring, popula- tion viability analysis, Zakynthos Island


The supplementary material for this article is available at doi.org/10.1017/S0030605324000140


Introduction


damental for their protection and restoration (Schemske et al., 1994; Yates & Broadhurst, 2002). Monitoring, includ- ing assessing range size, population dynamics and exposure to anthropogenic threats, is one of the core activities of con- servation biology and provides predictive power (Tienes et al., 2010). Long-term monitoring of marked individuals can provide information on vital rates (e.g. survival, transition between life stages) for estimating population growth rates and probability of extinction through matrix population modelling (Morris & Doak, 2002;McCaffery et al., 2014). Genetic information is important for managing threa-


K


tened populations and species, and variability within popu- lations is related to their evolutionary potential, which is often higher in more genetically variable populations (Hoffmann et al., 2017; Ørsted et al., 2019). Consequently, evaluating genetic variability is crucial when making man- agement decisions for threatened species (Weeks et al., 2011; Hoffmann et al., 2020). Genetic studies enhance conserva- tion effectiveness by identifying populations with low gen- etic diversity and predicting genetic drift effects (Nicoletti et al., 2012; Augustinos et al., 2014). Plant population monitoring is uncommon because it is


time- and resource-demanding (Heywood&Iriondo, 2003). In Greece, for example, despite the high number of endemic and threatened plants (Phitos et al., 1995, 2009; Dimopoulos et al., 2013), studies of their conservation biology is scarce (but see Valli et al., 2021a,b). Limonium Miller is one of the largest genera in the Mediterranean area, which is the centre of diversity of the genus (Brullo & Erben, 2016). The high diversity and complexity of Limonium is a result of the reproductive behaviour of the genus, which encom- passes sexual and apomictic reproduction, frequent hybrid- ization, and polyploidy (Georgakopoulou et al., 2006; Brullo


This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. Oryx, 2024, 58(5), 587–599 © The Author(s), 2024. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605324000140


nowledge of the life history traits, reproductive biology and demographic characteristics of rare species is fun-


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